sounds like you're creating UV mapping, but you're not sorting it so there's no overlap... you need to move the UVs around so they don't lay over other ones... that'll help to reduce the stretching you see.


also, with a complex model, don't just select your entire mesh and then choose planar projection... you need to separate your projections into parts to help avoid that overlap. even though it looks like a mess at the beginning, try automatic mapping... with a little work (sewing UVs, moving UVs, etc.) you can make it easier to paint a map in PS with less stretching.

take a look on the site: there's a few tutorials that deal with UV mapping later on...