Don't really have any good tips. Practice makes Perfect. So I guess you'll have to practice more artworks. Being genuine and special (thinking out of the box) also helps.
Ex-Gamemaster
Shoot me a PM if you have any queries!
ALWAYS ALWAYS have an full complete idea,every single detail of the head you want in your mind before drawing
Just to complete his/her statement, do improvisations wherever necessary.
Because you can't possibly think of every detail without really looking at it live.