Be eager for his cock and cum, suck for the love of sucking and take your time. Enjoy closeness to his cock and don't treat it as cum vending machine. Given care and time his load can also be larger so you get what you are willing to give. Many guys love eye contact. Consider him as complete person, not just cock and balls. Adore him. Be careful of teeth. You can't get rid of them (don't start) but you can cover them with your lips, cheeks and tongue. Suction is great. It pulls your cheeks and lips on top of your teeth and give sleek surface for cock to slide against. You need spit, a lots of it. Drool as much as possible. Good hydration is important, dry body doesn't produce as much saliva. Sometimes he can be willing to give his spit for lube, take it. Start slow, begin with adoring and loving kisses, licks and sucks and get more intense and lustful as you go. You can slow down when he is getting near and tease or edge him if you are able to but don't ruin his orgasm! Move your tongue. You can spin it around his cock head or do circles or zig zag on his frenulum. Bottom side of your tongue has different texture than it's surface or lips, they can give different sensations. Different sensations can keep things interesting. Just bobbing your head up and down is equal to higher temperature jerking off so be creative. If you have beard you might give just slightest of brush with that while you take couple of breathers. Some like that, but it can be quite intensive for others. Your jaw can, and probably will, get tired. Take a breather but don't stop giving attention to his cock. Licking his cock and balls can give your jaw a while to rest. Let your tongue dance on his cock head. Tiny circles to frenulum with tip of your tongue can be great. Warm, wet, wide and soft licks from his base to his head too. Using your hands can be controversial advice. They can be great tool especially if he happens to have really large cock. However some men dislike if you jerk them off, that is something they can do by themselves. Many guys love it when you play with their balls. Gently pulling on them while he cums can give great pleasure, but also licking, sucking, stroking or tickling them can be fantastic. One dude loved to shove both his nuts in my mouth and make me suck and lick them for multiple minutes at time. Give him what he wants. Learn to read his reactions and if he gives you straight directions, take them. Be supple, soft and easily directed. Aim to be not robotic and mechanic but more fluid in your movements. Learn to deepthroat. You probably won't be pro at once so practice with good sized dildo will help. Take his cum where he wants it. Many men like to see you swallow, but some may want to paint your face, those couple of seconds are special for him so let him do as he wants. You can eat it afterwards. After orgasm many men are really sensitive so all touching should be done really carefully. Some men like you licking and kissing his cock clean while others hate every single touch. Learn to know his needs and wants.
Wow, that became pure stream of consciousness. I don't even try to organize it. Sorry for all who try to get something out of it : )