Amature. Neither of my first times hurt, because my boyfriends were not total jerks who just went balls deep in a single shove. Was it great, no, but there was no pain. It's called taking your time.
I'm sure there are people out there who would never enjoy it and just from personal experience you enjoy it more as you get more comfortable with the whole process and get better and relaxing and letting yourself enjoy it. As for the technicalities, getting all the way in can take time but as long as it isn't dry once it's there you can be pretty vigorous without any pain. Some positions are easier and feel more enjoyable than others but that is true for anything. I'm a woman so a man's perspective might be different, but I'd say the real key is listening and paying attention and not trying to rush it.