1. 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.
2. When you purchase your aquarium and the equipment for your setup, do not purchase the fish at the same time. You are going to need plenty of time to cycle the water in the aquarium to make it hospitable for the fish in your aquarium.
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.