How to give a blowjob?

Please no critical comments, I just need advice. 
I've never given a blowjob before and I really want to give my boyfriend one. 
I have small lips and a tiny mouth. 
He's about 6 1/2" in length and very thick. 
I'm so nervous that I'll be terrible at it and he won't be happy with what I can give him.
Deep throats my immediately is out of the question but what kind of tricks should I do that guys really enjoy? 
Thanks in advance.