this fellows might help...
basictut1basictut2I used those two... for better results and preventing streched textures you need to "cut" the model into several pieces so that they appear separated from each other and the UV map stays as flat as possible, to cut use "seams" (CTRL + E -> mark seam).
I've found it easier to just select different parts of the body and then join them up in vertex groups so you can select and deselect as you like, then you press "U" -> Unwrap with the faces selected and on the UV editor you'll see the faces drawn.
At this point, identify the ones that seem to be streched or smaller and try making a seam on the mesh near that and then select all again and press U, this will update the UV editor.
Repeat the process with the different zones of your model till you get a fully flat image of the hole mesh, then just select all faces and unwrap again.
I'm just doing my first model so don't feel to confiden about my advices XD