Resources are raw natural goods collected in-game, which can be spent to create new units, structures and ammunition, power up weaponry or keep some systems functioning (like cloaking systems). In TA, two types of resources exist: metal and energy.
A Note on Efficiency
From the start of a match until the end, it is incumbent upon every player to expand, both in terms of territory controlled, and in terms of resources, which often go hand in hand. Most players begin with several Windmills or Solar Generators, expand with their first few mexs (metal extractors), and then build their first factory. Some never expand very far beyond this point. Even if you don't lose directly when you do this, you still damage your team's overall well-being.
Resource versus Military Spending
Your economy begins with a Commander, but quickly grows to include mobiles (units which move) and statics (units which don't move) of many types. The key to victory is knowing which units to build and when. Creating builder units, which in turn can create resources, is a high-priority process, and should remain so until the match ends. Each military unit built is a net loss from your economy until you put it to use. For example, say that you build your first factory, and that the first unit produced is a military unit - a Flash tank. Not only does this action consume resources that could be spent on resource generating structures, it delays the construction of units that could build more resource generating structures more quickly. You lose time, metal and energy. Economists refer to this as the "opportunity cost", what you lose by making one decision over another.
Builder units provide a direct economic advantage. Each additional builder means that you can build resource-generating structures faster. The benefits gained from an active builder quickly outweigh the opportunity cost of constructing that builder, as their activities result in absolute economic growth (You get resources faster). Combat units provide an indirect economic advantage when they destroy things your opponent's built or secure more territory for you. They result in relative economic growth by reducing your opponent's economy. (Your opponent loses resources) The efficiency of combat units is much less certain, and depends much more on the tides of war and your opponent's actions.
For the present, keep in mind that resource spending should almost never be 100% on economic or 100% military. The ratio should vary in accordance with need, but a generally healthy ratio is 60% Economic Spending and 40% Military Spending. Every rule has its exceptions, but, all other things being equal, the stronger economy wins the match.
The Relative Efficiency of Resource Types
So, should you build metal extractors (mexs) or metal makers? Windmills or Solars? How many, and in what order? The answer to these questions will vary from map to map, and from mod to mod, but can generally be predicted as follows:
A Solar Collector costs roughly three times as much metal as a Windmill and always produces 20 Energy. Wind is variable, but the maximum and minimum wind for a map can be translated into a fixed value by adding the two extremes and dividing by two. Always check the wind values in the lobby before the game begins! Picking the right level 1 energy structure is vital.
Let's look at an example. Take the map EvergreenHaven v3, which has Wind between 1-30. This gives us an average wind income of :~15.5 energy per Windmill. As you can build roughly three Windmills per Solar Collector, metal for metal, your Wind/Solar Ratio (Average Wind income/20 energy per solar) would be 15.5*3/20 = 46.5/20 = 2.325/1. On this map, Wind is optimal.
It is worth noting that Wind's variable nature can lead to unused excesses and unpredictable stalls, and that build times for the two structures are usually close, with Windmills building slightly faster. While these deficiencies can be addressed to a degree by building a minimal number of Solars to ensure a certain income or additional energy storage units (which are generally inefficient for small-scale use, but can be very good in large numbers), in the case of a Wind/Solar ratio of 1/1, Solar would be the preferred choice. As a rule of thumb, say that with a ratio of 1.2/1 (24/20) or less, build Solar. For 1.21/1 or more, build Wind.
On almost all maps, wind will be your best choice. Auto-spaced, huge box build orders for Windmills should be given to one or two level 1 builders early on. Spring makes this very easy to do - click on the windmill, hold down alt shift, and click and drag. You can use z and x or the 4th and 5th mouse buttons to adjust the spacing between units. Give windmills at least 1 unit of spacing, preferably more, as they explode violently when destroyed.
Geothermal plants should be considered carefully. They can give you a big boost to your energy, but are very tempting targets for your enemy and can only be built in certain places. If you have a geothermal vent that looks fairly safe and your economy's otherwise healthy, build one. Otherwise pass.
In almost all cases, metal extractors are more efficient than metal makers, so while a mix is usually optimal, the general rule is to always claim all mex spots available to you before producing metal makers. Please note that "mex spots available to you" does not refer to the initial three or four near your Start Position, but to all unclaimed ones. All other things being equal, all players will claim mex spots in territory covering (map size/number of players). If your enemy doesn't claim all the spots that are within their suggested territory, they're yours to claim as well. As you defeat enemies, it is of extreme importance to move forward and claim mex spots to enhance your own economy as you disable your opponent's.
A Note on Stalling
Don't. You should never try spending much more metal than you make at any given time unless you've stockpiled in advance, and it's even more dangerous to run low on Energy. Many weapons, including HLTs and the Commander's D-gun, require it to fire, and mexes require it to operate. If you want to build two things at once but don't have enough metal, prioritize. That way, one of the things will be finished in less time. Having many builders idling is a sign of poor planning. Having every builder building very, very slowly from a stall is just as bad. Given the flexible nature of energy and the disadvantages of running short, it is important to always have an excess available. When using metal makers, always use the Metal Maker AI. (Click the metal maker in question, then Click the "select AI" button then scroll down and select the "metal maker AI")
If you do start to stall, back off your military production as much as you safely can and focus on shoring up your economy. Stabilize your energy supply first, then work on building up your metal supply.
Teching Up to Expand Resource Production
Once you've got your level 1 economy on solid footing, you face the next problem: deciding when advance to tech level 2. Building a level 2 facility 5 minutes after everyone else has one is a better alternative than getting one 90% of the way built with no means to defend it and losing it to an AK. Falling badly behind in the Tech 2 race will hurt your economy in the long run, so it's important to know precisely when you're safe to build.
There are a great many variables involved in determining when it's best to tech up, most of which involve common sense. Don't start building a level 2 factory until you can defend it. Make sure that there are static defenses nearby to ward off attackers. Even a few LLTs in the right place can make the difference between a load of scrap waiting to be reclaimed to fuel your continued expansion and a triumphant army of Flashes sitting smugly by the ruins of your level 2 factory. As a rule of thumb, don't start to build a level 2 facility until you have 25 Metal income and 800 metal in storage. Trying any earlier will hinder rather than help. Trying much later will waste time that could be spent building Moho Mexs.
Unless you have enemies knocking down your front door, the first and second unit built from your level 2 factory should be advanced builders. Assign these to Ctrl groups immediately and get them building. If enemies have knocked down your front door, build the advanced builders the instant it's safe. You can't afford to get any more behind, but you also don't want your advanced builder to roll out of the factory and get instantly slagged.
In the case of XTA, you should have ample energy income at this point. 300 over and above what you're using is the absolute minimum, as each Moho Mine in XTA requires 300 Energy to function. For AA and other mods, excess energy is less necessary, but is still good to have. Remember, energy is what makes everything go. Run short on energy and your enemy will run over you. The first item built with your advanced construction units should usually be a Moho Mine on your biggest safe metal spot, followed by Moho Mines on all other metal spots available to you, or everywhere on a metal map. If your enemy's being particularly aggressive (or suspiciously quiet), a Radar Jammer followed by Moho Mines everywhere is also an option.
Once you have a few Moho Mines up, and your military (both mobile units and static defenses) is reasonably solid, start constructing a fusion plant or cloakable fusion plant. Defend these well, especially against airstrikes. Not only are they a hefty resource investment, but they go bang with extreme alacrity. A field of flak turrets and missile towers nearby (appropriately spaced-out - don't try to carpet your base with them!) will give any airborne visitors a nasty surprise.
Little is more frustrating than seeing an ally get to level 2 and then try to build an Annihilator or Doomsday Machine without a single Moho Mine to give the project the resources it needs to finish before the game ends. Level 3 factories (Experimental Gantries in AA) can come at any time after Moho Mines are built, and will be further discussed in Strategy, part 2 - Military Policy. In mods such as Final Frontier, where level 3 Builders with level 3 metal extractors exist, they can come earlier.
When It's OK to Stop Expanding Your Resources
Never. It is never acceptable to stop expanding your economy. You're beating your enemies with what you have and victory seems certain? Keep expanding, and pound them into the ground. Let your attack falter due to lack of reinforcements (or, worse, running out of energy), and they might fatally surprise you. You've hit the unit limit? Self-destruct level 1 or unused units and replace them all with stronger models. You should easily be able to turn 20 Windmills into 20 cloakable fusion plants at this point. Your enemies are pushing you back towards your base? More resources will let you mass enough military units to turn the tide.
In order to manage your economy effectively in the late game, you really need to use the features Spring offers. Otherwise, you'll quickly be overwhelmed by the number of things that need doing. Even something as simple as assigning the lead construction unit of each "task group" to your numbered ctrl-groups can make your life a lot easier.
- You have 10 Ctrl groups. Use all 10. At least four should be reserved for advanced construction units. Which four is up to you, but using consecutive numbers is probably a good idea. Save at least a couple of groups for your battle units.
- Issue Guard orders to give prime builders (at whatever tech level) assistants, creating a Builder Group. 4 Farks on an advanced builder more than quintuple its output, and are easy to handle if you Ctrl group the one advanced builder. If you have level 1 builders that've run out of things to do, assign them to guard a factory or a level 2 builder. As long as you have the resources to support it, the more builders on a project, the better.
- Use Shift to queue orders. Don't be afraid to build up really long queues. You can always cancel a queue, or even use wait orders to delay part of it until after a vital job finishes. You want to be able to devote enough time to your battle units to win fights, so you don't want to be babying your construction units all the time.
- Use Shift drag to create lines of units and Shift Alt drag to build boxes of units. These are especially good for defences or resource buildings, as they let you queue up a lot of orders very quickly.
- Use mouse 4 and 5 or z and x while dragging to adjust the spacing between line or box build orders, to make units much harder to chain destroy and ensure that your defensive structures have clear fields of fire. Play around to find the right spacing for a given building. Some have bigger explosions than others.
- Use your Commander intelligently. He can't build much by himself, but his nanolathe is almost as powerful as an Advanced Construction Vehicle's. This can be used to speed up construction significantly.