Personally, I don't believe in practicing but heck, if it gets the job done, rehearse, rehearse, rehearse! The best way to turn your man on with dirty talk is to tell him what you would do to him once you get together.
Then I want you to take your time as you lick it all off.
An easy way to do that? Do you have any preferences? Jump in and wait for that dot dot dot.
If he asks for phone sex.