One of the best things that I have learned in all my years of owning fish tanks is that you should always figure out what type of fish you want to get before you go out and purchase a tank.  Too many times, I have seen people come into the fish store and purchase a tank.  A month later, once it has cycled, they want fish that will not work well in their tank.  For example, hexagon tanks are really beautiful to look at and they fit well in most corners of a house.  The problem is that most hexagon tanks are created with a lot of length and not much width.  This causes problems for fish that like to swim back and forth.
    A hexagon tank works well for fish that don't swim very much and like calm waters with not a lot of other fish darting past them.  Fish like angel fish and discus fish do well in tanks like these.  Other fish that do well in this tank are fish like marble hatchets and cat fish because they are top and bottom feeders.
    It is always best to start out with a small tank, if you are just getting into the hobby.  This will limit you to the amount of fish you can get and also let you know if you like the hobby you are getting into.  You spend less money when you start small.  The one thing that discourages more people who first start out in this hobby is the amount of money that they spend and the fact that no one ever told them how to care for their fish.  Once their fish start dying, they get discouraged, get sick of spending money, and wind up selling their tank at a garage sale.
    It is my advice that you should wait until you learn more about the fish you want to buy before you purchase a big tank.  This will allow you time to get to know your fish and what else is out there and it will also keep you from "flushing your money down the toilet."

Once you decide on the tank, you are ready to go onto Things to consider and going over your check list.