ropical fish guides can help you decide on how to populate your new aquarium. These books will describe the different varieties of fish available. They will also go into some detail on their preferred habitats, whether they are placid or aggressive by nature etc. You should also be able to find out which species can co-habit and what species to avoid altogether in a mixed environment.
The more common types of tropical fish are available at most pet stores or your local aquarium outlet. Most people will want some Neon Tetras as they are very attractive with their bright colored bodies. They are also a very peaceful fish so you don't need to worry about them fighting.
The tropical fish guides will also give you some directions on how to set up your aquarium. The most obvious is whether you will use freshwater or salt water but that is not the only consideration. Some varieties of fish are rock dwellers and to flourish they need some of their natural habitat in the water. Others are used to living in the Coral reef so would prefer a tank with some coral material in it. You should be trying to replicate their natural habitat as much as possible and all questions you may have should be answered at least in part by the guides.
Your guide will also give you some direction on the size of tank required. Some tropical fish need more space than others and one of the classic mistakes beginners will make is to buy too many fish for a small tank. The water will need to be regularly checked for nitrate levels. The position of the tank is also important as you cannot have fish situated in direct sunlight or over a heater.
There is a lot to owning fish and reading some tropical fish guides is only the start of your education!