heres what i would do if i were in your shoes: Get the tank up and running. By this i mean adding sand and Live rock if you plan to keep it. IMO live rock is a very wise choice. In a 30 gallon tank you really wont spend much money on it. I would by one 20lbs bag of dry argonite, no need in spending the extra cash on live sand if the tank is not intended for corals right yet. Once the rock is added your sand will begin to cycle as well. After this is done, the tank will need to run for about 1 month before your first fish is introduced. In this time about 2 weeks in you can add a few hermits to help maintain the algae you will have after the tank cycles. This is normal and regular water changes and tank maintanence will prevent a major build up. After the 1 month period you will want to test your water to make sure both ammonia and nitrite are 0. If this is the case, do a water change and then add a fish. If your really worried about what you can keep, check out Liveaquria.com. They have detailed pics of fish and tell you information on each fish like living conditions, feeding etc... Id look in the gobies section and beginners section. Also be sure to stay clear of damsels, there purchased by beginners on a regular basis, only to find later that you'd preferre not to have those fish do to ther aggressive nature. Once you've had the tank up and running with fish and stuff, be prepared for a larger tank, I feel you will want one lol. good luck and be sure to keep asking them questions. The more the better.