As for tips; 7 gallon is very small. This limits your livestock options (2 damsels is probably already maxing out your fish), and will provide a challenge with keeping the water parameters stable... which is a challenge if you want corals. Stability is key in this hobby.
Anyways... don’t be discouraged if it seems difficult. By choosing a Nano tank, you’re attempting something challenging as your first tank. Bigger tanks are easier in many respects. It’ll be a learning process, but be patient and you will learn and grow!
Also, invest in a Refractometer (not a hydrometer) and a cheap glass thermometer. Those two tools will help keep your salinity and temperature in line. And they will be your best friends.