Well, for me, I usually start by caressing it gently. Don't neglect the inner thighs too. Then I'll lick the head of it some (just the tip) and tongue under the head. You can do this while you LIGHTLY massage his balls (I say lightly because I was with one guy who had sensitive ones that started to hurt when I massaged them). Then take just the head into your mouth, and sometimes (in my experience), it can be sexy for a guy to make eye contact with you while you're like that, so I'd look up as you're doing that. Curl your bottom lip over your teeth like you're imitating an old guy who has none and just begin lightly sucking, slowly easing your way down it. Don't take it too fast or you'll gag to the point where you'll have to pull out and will feel like you're going to throw up. Just slowly. You're in no rush; just let it happen. And just make a gentle rhythm with it, tightening your lips a TINY bit over it each time your head goes back down. Now, when doing this, I usually try to get my head on the underside of it so when I go back up the tongue touches the underside of the head each time and stimulates it. This can also help you eventually take more in and swallow the head to deep throat it. And DON'T FORGET TO BREATHE THROUGH YOUR NOSE! Nine times out of ten, your mouth will get sore faster without breathing through your nose. At the same time, if your mouth starts to get sore, pull off and just lick the length of it and tongue the head to get some breath back. You can also suck down the sides of it (lightly, mind you) during this time to keep it wet (so it's easier when you go back to having it all in your mouth).

While you suck him off, you can gently stroke his balls to increase stimulation. I'd normally place the sac between my index and middle finger in the back and thumb in the front. Apply just enough pressure that he knows it's there (like you're gently petting a cat) and just stroke downward over and over. And if he's completely naked, you can gently reach up and massage his nipples to also increase stimulation. And sucking while stroking the balls and massaging the nipples all at the same time actually made one guy go wild moaning on me.

That's my technique. While I've never heard anyone say I'm the "best," I've never heard a guy complain either. I hope this helps.