The main key is learning to relax your throat. I have a very strong gag reflex, and haven't quite mastered that, though. A shrink I saw once said, as far as the taste of the semen, if that bothers you (it does me), is to make sure the head of the penis is at the back of your throat when he shoots, and swallow as it hits the back of your throat, rather than your tongue. I never got a chance to try it, since we haven't had sex in eight years, but maybe it'll help you.