1. Cichlids tend to be very intelligent fish. You should do your best to interact with them as some species will respond positively to you arriving home. These fish are very active and if you interact with them, they can develop much better.
2. It is generally a good practice to purchase the largest aquarium that you can actually afford. A larger aquarium will be less susceptible to quick changes in the chemistry, and will offer much more stability.
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.