remember that you're writing with somebody else, so the thread isn't all about you. read over your tag before you hit post and see if you gave the other person things to respond to. if it's just your character moaning and writhing, don't hit post. your character's moaning is only interesting to you.

think about what your character's body is doing. are they enjoying what is happening or are they fighting back? are they restrained, either verbally or physically, or can they touch the other person? don't be afraid to be detailed in your descriptions.

are they gagged, or can they talk? if they talk, have them say something more than "oh yes harder". again, that's only interesting to your character. it's okay to have characters having a conversation while they're fucking.

what emotions are they feeling? are they scared? nervous? eager? desperate? how are these emotions expressed physically?