I have a 512x512, and I use a uke-like version custom head.
Eh, it misses a lot of details obviously, and its a waste for a 512x512.

I am looking for a tutorial to draw textures with brushes or stuff.

all my previous texture is designed by shapes. Im about to give an effort to draw my own new texture

Try some of the threads in the forum link I gave you. It'll help, I know it.

http://forum.toribash.com/forumdisplay.php?f=510