This is a good introduction to texture painting done entirely in Blender.

Originally shared by Serene Jewell

This is a good introduction to texture painting done entirely in Blender. He's using Blender 2.72 rather than the current 2.76, but the process hasn't changed much. I think this whole series is a good intro to low poly creation in Blender for things like Unity and OpenSim.
http://www.youtube.com/watch?v=Hr_itixx0Yo