Ok so here is my first head texture.. It didn't come out how I was expected but still want some feedback...

the number one thing most people do is try to work with a square drawing, imo that's a big no-no. try using a drawing that the width is twice the height.
1024x512 works best

also, the shadow on the hair is too bold. use a burn tool or a low opacity black brush to shade

I recommend using this:
click me

It will help you map a head texture easier. Keep those eyes farther away from each other.