1. Having a quarantine tank on hand is a very good practice to use if you frequently buy new fish. The quarantine tank will weed out any sick fish that could possible get into your aquarium and cause harm to the other inhabitants.
2. It is never a good idea to add shells from the beach into your aquarium. Introducing shells raw from the beach can add harmful bacteria and potentially new creatures to the aquarium.
3. Make any adjustments to the placement of the decorations in your aquarium before you fill up the aquarium all the way. Not doing this can cause an overflow when you reach into the tank.