That, coincidentally, is why that I and many others detest UV mapping. It's like mowing a lawn with a hedge-trimmer. You have to painstakingly assign each cluster of polys their own section of the texture space, carefully ensuring mirroring is done right and that pixels aren't being skewed the wrong way, that the places that need detail can get it and the places that don't don't waste it. Avoiding distortion is a trick too.
Fortunately, there are apps that will handle it for you - there are numerous auto-unwrap apps of dubious reliability that will get you something to draw on in a moderate amount of time.
