You really should do more planning then 6 minutes. 30" tank, what is the height and width? Are you looking aquatic, semi aquatic, or not aquatic? There are lots of different species you could keep, you really need to be specific.
How about you do some research on species your interested in, instead of thinking we'll toss you a bunch of helpful stocking suggestion in 6 minutes when all you tell us is "30 inch tank".