Ash,
I would suggest you go through this thread I started that deals with observing the Moon and planets:
Observing the Moon and planets - the good juice and cheats
It discusses not just things to explore on the Moon and planets, but also talks about getting the most out of your scope with understanding its limitations along with tips and tricks.
Also discussed are filters for the Moon and planets.
If you only have 30mm and 15mm eyepieces, I would also suggest you invest in a shorter focal length eyepiece right now than a filter. An 8" dob is a marvelous scope that will give you many years of good service. A 5mm or 6mm eyepiece will give you not only higher magnification, but will also be less brilliant on your eye. Look for an EP with at least a 58° apparent field of view, as this will give you a longer drift time than a plossl eyepiece for the same focal length.
If you would like a couple of eyepiece recommendations, just let me know as at this point in your thread it is beyond the scope of the thread. And you don't need to burn the Big Bucks to get a very good short focal length eyepiece.