Well, guys like it when a girl pays attention down there. I haven't met a guy yet who didn't like a bj. The sensitive areas are on the bottom of his **** and around the head. Licking it up and down like a lollipop is a nice way to start. Pay special attention to the area around the head of his cock. Some guys like it when you kinda swirl your tongue around the head and lick it as you take it just in to your mouth.
Taking more in your mouth is kinda up to you. If it's uncomfortable to take more because of a gag reflex or something, then just do the head of it and stroke the shaft with your hand while you suck and lick the tip. Like when a guy does you, it's good to find a rhythm that he likes and gets into.
If you have any question about what he likes, just ask him how he likes it.
As for where he shoots, that's up to you too. If you like the taste (I do, but it's kinda an acquired taste I guess), lots of guys get turned on by cumming in your mouth. Otherwise, let him come on your tits. That's pretty sexy too. Some guys like to come on a girl's face and that's ok with me too but don't get it in your eyes! It stings pretty good.
Anyway, be real careful not to use your teeth when you suck him. That's a definite erection killer. Anyway, have fun with it. Think of it as the ultimate kiss and you can't go wrong.
the secret is in the hand. Learn how to stroke a mans penis well. Add your mouth to that. Use lubricant if you can, your lots of saliva with the hand movement. Going really fast is not a necessity, but keep the sensuality of the movement. Avoid using your teeth, when you employ your mouth, and basically keep the rhythm steady. You should be aware of the different stages of arousal. its similar to your own, but probably more compressed. When he's in a highly aroused state, the penis is totally erect, you may want to increase speed a bit with your hand, but keep it smooth, and not too rough. Use your mouth to suck the top, lick, etc.the guy below me had some decent ideas. Avoid teeth.that hurts and will be a turn off
I suggest you get interactive and ask what is liked etc. even suggest to the guy that you want him to teach you how to do it better. (I'll help if you want :) ) Anyway. back to the subject at hand. licking up the length is great. You definitely want to put it into your mouth. the more the better, but don't gag or hurt yourself. The sensitive place is just under the head on the down side of the penis. Make sure to use lots of tongue action there. Use one hand to jack it off . what your mouth can't take. but don't grab the skin too close to the balls or that will hurt. Using your other hand to massage the balls is a very nice thing. occasionally licking down and sucking one gently into your mouth is great too (but keep the hand on the shaft moving while doing this.) Swallowing is really nice thing. but only if you want to. Coming on the breasts is great too. Just show some enthusiasm and show that you enjoy it. remembering the brain is the most import sexual organ there is. so it has to be involved as well. and guys love it when they know a girl is enjoying doing that.