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. 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.
3. Cloudy water is normally a sign of overfeeding your aquarium. Judge the right amount of food to place in the aquarium to not leave too much residue due to overfeeding.