blowjob tips ?

Weird question I know , but I need some tips please .

My boyfriend and I have been together for almost a year and we started being sexual the first month we started dating . He loves giving me head and loves getting head but I just can't seem to do it . Like I can but I can't stop gagging and coughing . It's so embarrassing and I want to please my man with out making those disgusting sounds or feeling like I'm gonna throw up on him . At first I couldn't stand the taste and smell but I got used to it and we bought a warming strawberry jel , and that works perfectly .

Then we got a numbing spray specifically for deep throating but it stops working in less than a minute .

Really I just need tips on how to stop gagging and be able to give him good head when ever he wants .