1. It is not advisable to leave your aquarium lights on at all times for the aquarium. You should keep the lights on for 8-12 hour periods at a time. If you want to keep the tank lights on when you arrive home, simply get a timer for the lights so your fish stay on a schedule.
2. 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.
3. Try to provide an environment that is as stable as possible, fluctuations in the aquarium can have a negative impact on the aquarium. Try to keep the temperature and PH levels fairly balanced in your aquarium.