Did you know that a new aquarium can develop a pressure crack in the glass and lose all of its water in a short time?
To prevent this, make sure your aquarium is set on a flat, strong surface, such as an aquarium stand.
If your tank wobbles from corner to corner when it is empty, you should find a more suitable stand or shim with plastic strips or something similar.

Setting up and maintaining an aquarium should be a relatively easy endeavor.
Make sure that you buy a large enough filter. Buy one that is larger than the manufacture recommends for your size aquarium. It is also best to use an under-gravel filter with a power head and a power filter.
Most dirty aquarium problems are the result of putting too much food in the tank. For the average fish, feed just a couple of bite size pieces 2 to 3 times per day but never allow food to accumulate on the bottom of the tank.