1. It is not recommended to keep your aquarium where it receives direct sunlight. Exposure to direct sunlight can upset the balance of the aquarium and can raise aquarium temperature levels. It is best to keep your aquarium in a place where you can control the lighting.
2. 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.
3. Some people go by the ìinch of fish, gallon of water rule when deciding on how large of an aquarium to buy. This is a completely false and bad method to go by, you should always check your individual fish's tank requirements.