I have been giving blow jobs to the same man for 10 years, and although he has enjoyed them all, from my first, wet lame attempt to the most recent my technique has improved greatly with practice, and it is at his request I share this.
I don't think position matters a great deal for either party, providing you are both comfortable. He needs to be able to relax and enjoy himself, you need to be relaxed enough to focus on his cock. I normally find kneeling between his legs while he sits on a comfortable chair, or kneeling on the bed between his outstretched legs as he lays back work best for us, but experiment with different positions till you find one that suits. You might find that him standing, you kneeling at his feet exciting, something kind of slutty about kneeling at a guys feet and sucking his cock while he stands above you; be careful though as he has to not quite let go, not totally relax, or he will fall, probably taking a fist full of hair with him as he goes!
Anticipation is a good place to start, if he knows it is coming it builds the excitement more. Look into his eyes and kiss gently down his body, let your fingers trail over his body, resist the urge to go straight for his dick though, if he is laying below you as you move down his body let your nipples brush against him, not only will this feel great to you but for him also. As your chest reaches his cock press down slightly letting him sit between your breasts as you suck and kiss his belly. This will drive him wild.
As you lower yourself further lick up the stem of his cock with your tongue, base to tip without touching it with your hands. Do this slowly and as you get to the tip look him in the eye. If he is looking at you this will intensify the situation, bringing the two of you closer together, if he is looking elsewhere, the ceiling perhaps, or has his eyes closed it will give you a sense of how much he is enjoying it.
Lift his cock into an upright position, with your hand and slowly bring your hand up and down, after a few strokes place the head in your mouth. Make sure before doing this your mouth is good and wet. Slowly run your tongue around the head of his cock while holding it in your lips and holding the base with one hand. Do a couple of circuits before gently sucking, again just on the head. Slowly increase the level of 'suck' you are using, until you are sucking reasonably hard, but keep your hand still and do not go lower then the head. Then return to the circling motion. The sudden change between hard sucking and gentle liking will not only surprise him but also increase the sensation.