My advice would be to think about it before you go into it and formulate a vague (or in depth) plan of action. So I am going to do this, then this, then this. Of course it might change during your play time but having some kind of plan will give you a bit more confidence knowing that you wont suddenly freeze up and wonder what to do next.
Here are some things we enjoy, maybe you can add the ones you like the sound of:
Making him ask for permission to cum, when he does ask, tease him "Is that it? That doesnt sound like begging. Clearly you dont want it badly enough" Tease him right to the edge, you will be able to get him as close as possible if you make him tell you when to stop. To turn this into a dom thing I usually say something like "You don't have permission to cum so you had better tell me when to stop or someone will be in trouble" Any kind of delaying, teasing and denying his orgasm is all good. When you are ready to let him cum, instead of just saying "Yes" I once played a game with my guy: Basically its called the two second rule. I get him to the edge and he tells me to stop but I only allow him two seconds rest to pull back from the brink before I stimulate him again. Of course the "stop" starts to come quicker and quicker and within 30 seconds he will likely cum. Then I get to smack his ass :D Orgasm play is a massive turn on for us and it holds a lot of power.
Tie his hands and feet and then sit over his face, not quite near enough for him to be able to lick you. (Tell him no touching) Play with yourself, use toys/dildos, finger your bum...whatever you know rocks his world and occasionally lower yourself on his face just to his lips and say "No touching" then back up again. I occasionally let him have a lick, coz I am sweet like that lol. Any cheekiness and simply pull away further..
Speaking of cheekiness, if he ever does break one of your rules or pushes his luck there are some things you can do to tease him like climbing off him, blindfolding him and saying "Now you dont get to watch" Then go back onto his face and continue masturbating over him, occasionally lowering yourself again. You can ask "Are you going to be good now" to remove his blindfold again.
Something you could do with the blindfold thing is to not use it and make him close his eyes instead. This is gunna be harder for him to do, esp if you are over his face masturbating but demand it and if he fails...take away his cookie. :D
We kind of enjoy slight humiliation play as you can probably tell lol, which brings me to my next point, if you wanna make him feel naughty for cumming without "punishing" him, you could try placing a pair of your favourite pants near his penis, or even cover him with the bedsheets while you play. Basically the idea here is to let him know that if he cums, hes gunna cum somewhere that you wont be best pleased about. I also once took him close numerous times then pulled up his jeans and buttoned them up and then straddled him and dry humped him. Because he was already so close he came in his pants, that was hot, especially hearing him say stop stop....nope! lol
Another game to play during his begging to cum....wait a few minutes until the sensations have died down a fair bit and then say "Aww baby you wanna cum? Ok you got 5 seconds" Then give him oral or a handjob or sex for that amount of time and climb off saying "Clearly you dont wanna cum that badly eh" lol
Ok I am evil.
Generally you want to think about things you will give him as a reward and things you will deny him as punishment. You may also consider incoprorating some anal play or threats of pounding his ass with that strap-on
Im gunna stop now before this turns into an essay but have fun!