How to make textures for Models?

Hey guys i was wondering , how do people make textures like that ?

i have other human textures but not like that , just full human and clothes seperated only , so how
i split them all and make them look like that so blender can read it correctly?

thanks but i want specific guides…
pyro send me fast and thats not worth of trying

JA ur tuts is little confusing :S
any specific showing ty.