Deffinatly do cardio. This will melt any extra layer of fat on your stomach, leaving just muscle to work with. Plus it's great for your heart.
Second, do about 40-50 crunches a day. No more than this though; if you do too many, the process will be slower.
Perhaps you could take up yoga as well. It's awesome for toning and really helps you relax.
I highly recomend it.