1. You should be sure to rinse out all of the materials you are going to be placing in the aquarium with water. Do not use soap or detergents, soap can cause toxic results for the fish in your aquarium. Just rinse the equipment with distilled water.
2. Make sure you ask plenty of questions when you are buying accessories or fish for your aquarium. The salespeople are there to help you, and should be able to handle any concerns you have when buying items for your aquarium.
3. It is generally recommended to use natural gravel for the aquarium. Colored gravel can be used, as long as it is professionally made, certain cheaply made color gravels can be toxic to fish in your aquarium.