The best advice I read on dirty talk (and sorry for the lack of credit where it's due, but I have no idea where I saw it first):
1. Say what you are going to do.
2. Say what you are doing while you do it.
3. Say what you just did.
This is cheap and easy advice, on the level of Sam Kinison's alphabet, that seems to work well. If you use a slightly lower tone of voice and feel like you are into it, all the better.