I use Wings3D, I guess that this would mostly refer to users of it. It may help others also.. I may also use pictures to demonstrate.. I will edit this post if I have to get off, or if I have other things to add... On to the rules..
1. Coherent models!
Example: An Anti Air Humvee...
The turret, the slanted square with the launchers attached, will be the targeter of Y axis. Something has to turn to face the target, if the weapon isn't stationary, or stuck in one launching area.
The launchers must be able to aim at aerial units. They must be able to move up and down the X axis. This way, nothing should look too bad, cuz it won't be turning the launchers through the body.
2. Details, details, details!
Or not. If your unit is going to be a midget, don't waste 300 polygons making sure each bolt has the wheel in its correct place. Some details (or most) can be completely ignored while modelling, and instead, made in the UV Map (I may include a tutorial about this, after I learn it much,much more.)
3. Joints...
Are not as important as some people think. If it is going to be a small joint, pay it no heed. If it is large, make sure to make it look like an actual joint would.
(Yeah, it sux, but ignore that part. Look at its knee caps...)
The knee caps, only are about 10 polies each. They are round, and hold the place fine, I even wasted about 3 making sure it would fit nice and snuggly.
4. Wasting of polygons..
Is really easy to avoid.
This guy
Had an insane amount of polygons, at least 3500 (I think it was twice that... Heheh.) And I cut it down to 700, in less than 1 hour. It took no time.. Let's break it down...
Cylinders - Never need to be more than 8, almost fine and dandy at 8.. In my model, there were 16 polies, it was a waste.
Sphere - Never use a perfect sphere.. Ever! I never have, and might if something is humongous enough to need it.. Click the little bar thingie to the right of it, and set it to 6-6 or something..
Chopping - I call it... I chop, for many of my joints. Cylinders can make some exotic forms if you connect a few vertices. Then extrude, plenty of things to do...
5. Tools
Wings3D has many tools. I like bevelling and connecting.. Move normal is great. Play around with the many things you can do in Wings3D. Wings3D can do anything anything else can do. It just takes some skill..
Hope anybody who read this learned from our "Newb to Newb" talk..
Have fun modelling...