I'm a very talented cocksucker and have sucked and swallowed hundreds of cocks. Here are my tips:
1. It's not just about the cock - lick and suck on his balls, lick his taint, run your tongue around his asshole, reach up and rub his nipples, explore all the "hot" zones.
2. Alternate between deep throat swallows and sucking/licking the head - concentrate on the underside of the cock, right below the head.
3. Look into his eyes as much as possible, don't be afraid to be verbal, tell him how much you love his cock, how good it tastes - eagerly lick up and swallow any precum.
4. For some men, mouth action will never be enough stimulation to bring him to ejaculation. If you use a hand/mouth combination, stoke the lower part of the cock and continue to lick and suck on the head.
5. Be eager, enthusiastic, and desperate for his cum - definitely swallow. Let him see his cum shoot on your tongue and in your mouth and then swallow it.
6. Continue to fondle, lick, suck his cock after he cums, more cum will ooze out - it's one of the best parts for me. Continue to lick his inner thighs, balls, taint, asshole.
Good luck, my friends!