You will also want to be sure of your location, because moving the tank after it is set up IS NOT a good idea. The gravel that will cover the bottom of the tank is heavy on its own, add an additional inch or so of water that you will be unable to remove from the bottom of the tank and the weight will double. If you try to move a tank that has gravel in the bottom of it you can break the seal that is along the sides and bottom, or crack the glass. Not to mention that scooping out wet, dirty gravel is not a pleasant job, to say the least. Put your fish tank in a room that you spend the majority of your time.
Fish can be entertaining and very relaxing to watch.
I once had an Oscar that would do all sorts of entertaining things to get and keep my attention. The next thing to do is to decide on the size of your tank. The size of your tank will dictate to a certain degree the kind of fish you can get. Obviously a two or five gallon set up will not work for fish that will grow very large or are big to begin with and will only get bigger. Some fish will grow only as big as their tank will let them and others will continue to grow no matter how small their tank is.