I just draw my own hand.
If it's realistic, maybe draw your own or someone elses. If it's cartoon/mangaish, look at the cartoon/manga you like until you find one that's like the pose you want.
I don't know..... Make sure that the middle finger is longer than the other fingers, and if it's bent, make sure that it looks ok if you open the hand you drew as well.
Do I make any sense?
Sorry that I'm not able to be so helpful