Find a position that works best for both of you, depending on where you are. Kneel before your man with him standing if you're in a confined area, or when you want to strike a pose that is really hot. Other positions: seat your partner and crouch between their legs (slide a pillow under your knees if you're not on a soft surface), or lay down and let your partner thrust into your mouth, (harder to control the depth, but good for you lazy types). If you're in a car, your partner can lay down lengthwise in the back.
A sexy way to set the scene is to use your mouth to put the condom on before you get busy.
If you're dealing with a soft penis, you don't have to wait until it's hard to start the show. Put it in your mouth when it's soft (or semi-hard) to get acquainted. Kiss it. Lick it. Explore the different textures, especially the roughish tender head and the soft skin of the shaft. Feel it growing in your mouth.
Slide your lips gently over your teeth for smooth sailing. Most fellatio recipients like lots of spit, but others prefer a drier job, so check in with your partner. Asking quick yes or no questions like "want it dryer?" or "more spit?" can be helpful and hot. Despite your amazing technique, you aren't a mind-reader, so watch your partner for body language cues. Heavy breathing and moans of pleasure are signs that you're on the right track.
You can do more wonderful stuff with your mouth than just suck. Mix it up by licking the sensitive underside of the shaft, the nerve-ending-loaded head of the penis, and the testicles. Softly blow on the moistened areas. The combination of sensations will feel incredible.
Give your blow job a hand. Grip the cock around the base and slide it up and down, hand-job style, in tandem with your mouth. This is great because you can cover a lot of the shaft this way without worrying about taking the whole cock in your mouth. You can concentrate on the super-sensitive head and suck as hard or softly as you'and your partner'like. Use lube for extra slipperiness.
Deep-throating the act of taking the entire shaft into your mouth and throat can be cool, but you can give a perfectly stellar blow job without doing so. The key to deep-throat is to relax your jaw and throat muscles as much as you can. Otherwise, you trigger the gag reflex.
Look at your partner and the ecstacy you have caused! Make eye contact. Show your partner how much you love being down there. Moan, make appreciative noises (a well-placed MMMM! can make for some nice vibration, too), let your partner know how turned on you are. Don't neglect the rest of the body, either stroke, tickle, scratch the thighs, stomach, butt, and everywhere else you can reach.
It is ultimately your choice whether or not to swallow. Your partner's diet, health, habits and frequency of ejaculation will determine the quantity and taste of the ejaculate. The ejaculate of someone who ingests lots of red meat, caffeine, alcohol or cigarettes, may taste more intense than that of a non-smoking vegetarian. The most ejaculate you might encounter is a teaspoonful or so. You have several choices if you aren't crazy about ejaculate, but don't want to hurt anyone's feelings:
β’ you can take it in your mouth and discreetly deposit into a nearby towel
β’ as your partner approaches climax, withdraw and finish with your hand.
β’ You can let your partner come on your body and admire the copious amounts of ejaculate