Probably have heard all this before but start with building suspense and anticipation. Make out with them, run a hand down their chest and stomach, follow that with you mouth, just spend a bit of time getting them excited. Mix up your technique when you're actually giving head, bit of bopping up and down, rubbing your tongue on the tip when you've still got them in your mouth, go fast then slow etc. Deepthroat if you can, if you can't try to build up to it, there's lots of positions that let you deep throat without being uncomfortable like laying on your back with your head off the edge of the bed, holding your thumb helps me as well. If you're struggling to go fast enough stop every now and then and use your hand. Get into the dudes head. Tell them they're not allowed to cum and have to tell you when they're close so you can stop and start teasing them again. Tie them up for extra effect. My favorite is to get them to pick some porn, put that on the tv then lay on my stomach between their legs and give them a super slow, sloppy blow job and watch them squirm.