I think enthusiasm is probably the biggest factor. IMO, That's not something that can be taught. Ya either like it... scratch that... love it... or you don't.
I was seeing a guy earlier this year who was over 7' tall. We hadn't done anything but kiss yet and he alluded to, ahem, "things" being proportional. I told him that I had concerns about that. He assured me that he had he'd be gentle and go slow. (He was a sweet, gentle, kind soul... a true gentle giant so I had zero doubts about this) I looked at him and said "no, I'm not concerned about sex. I'd hope that you'd make sure I'm ready and to not be rough. I am worried about blow jobs. I love oral sex and if I can't fit you in my mouth or get a tired jaw quickly, I'm going to really miss it." He said that he really didn't enjoy blowjobs and never came from them anyway. I looked him square in the eyes and said "this isn't about you. This is about what I enjoy... you're just lucky enough to be along for the ride." He audibly gasped and growled "That is the hottest fucking thing anyone has ever said to me..." And I felt his massive boner straining against his pants. Things progressed pretty quickly after that point... and i ended up giving him a BJ to completion. When he came, he actually roared. Literally roared. When he came back to earth, he said "oh my God... THAT'S what I've been missing out on all these years??? Thank you for showing me what they're supposed to be. I take it back. I DO like blowjobs. I like YOUR blowjobs. Im so glad you like doing that. You can take me along for a ride anytime you want." He was a blabbering idiot for a couple minutes and I just giggled.
I think my technique is plenty fine, but what guys have remarked on most is that it's apparent that it's not a chore or something that I do just to get oral in return.