You can practive cav by joining a duel server (when there is a good amount of ppl on, like before a strat battle) and just riding around lancing people. You lance will go through them, but you can learn the timing and movement of the horse.
You can do the same with ranged. Again, you don't get the same feedback, but you can generally tell if you get a hit or not.
Alternatively, siege is a great server to practice on...because of the respawn you spend less time dead and more time playing. Not so good for cav tho.