The answers to this question vary, depending on personal preference . Personally, I ride Shimano SPDs - always have, and always will. I don't have an issue clearing mud, and I can ALWAYS get out of my pedal when necessary! A good stiff-soled MTB shoe with some tread is a must, as you will be doing some running in said shoes as well as the riding. Toe spikes are good, and can be gotten pretty cheaply if they didn't come with your shoes. These will help on steep uphill runs, or in the mud.
Have FUN! CX is a blast, and my first race of the season is also this weekend!
SheFly