Beginner Texture painting a mushroom. Nice paced video. Start easy.
Easy to understand basics
He easily creates a texture with no seams on his objects. Very easy.
There are more methods on how to add detail to your textures. This person goes over several, one being stenciling. Great for decals.
This tutorial talks about something I didn't even know Blender had, Sort of a layer system like photoshop for texturing. This is something Blender needs to make texturing easier, but Wayward arts tutorial shows you how to set up a node structure to paint color, bump, metal all at once. He has a mask plugin that looks great too.