Best advice I could give without being there

is to keep it wet, concentrate on the bottom side/head, and use your hand(s) in the process. I like it when the hand basically becomes an extension of the giver's mouth. That makes it feel like deep throating even though it's not. It also makes it a little easier for the giver, especially if the penis is rather large. Using one hand as the extension of the mouth and the other hand to caress the testicles, butt, etc. is usually pretty darned nice. As he's about to cum slip a finger from that extra hand in his ass and he'll be screaming.
Oh, and watch the teeth!
I don't know about swallowing. LOL