I used to co-own an exotic and fish pet store, so i'm glad to help here.
First off, a 30 gal is neither large nor tiny, and you have many options available to you in terms of stock choices. If you like Loricariidae catfish (plecos and panaques) then you might want to consider making a tank around them, and only getting a few tetras to inhabit the midwater range. There are a TON of small, colorful pleco species, many of which also have really interesting behaviour as well. For most of them you will need some current (provided by a powerhead or a powerful filtration system), soft ph water, and most like driftwood to hide in and nibble on, Contrary to popular belief they do not consume common tank algae unless there is nothing, and I mean NOTHING else to consume. Many are omnivorous, and a few turn carnivore as they age.
Planet Catfish is a good place to start looking for interesting species. The care is similar for most of them.
For new tanks you can often purchase live bacterial cultures to help jumpstart your tank. Adding cheap fish is another. If you are patient then waiting 14 days before adding the first test fish is recommended. YOu can also get filter scrapings from your local fish store to add to your cultures. this is awesome if you can your hands on some. If you only have corporate stores in your area, this may be more difficult. Ordering fish online is simple and fun if you cannot find interesting or healthy fish locally. Be certain that the dealer has a phone number that works and use it to confirm your order.