1. You should never add uncured live rock to the aquarium. Doing so can release harmful levels of ammonia into your aquarium.
2. When you are picking out fish for your aquarium, you should always pick the best specimens available to put 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.