Old Perfecto Hood,
Hagen Aqua-Glo 15watt,
Read forums, read articles, read read read. Then when you've gotten sick of reading, talk to whoever you can that has ever kept fish.
Danios (all kinds),
Brazilian Swords (mine do fine submerged),
Mondo Grass (mine does fine submerged),
The first shall be last and the last shall be first
Just got into the hobby.
Keeping anemones in a reef tank can be a challenge if you are not fully prepared.
Cultivating a nano tank can be an exciting challenge but unless you choose the right fish for your tank, you may be in trouble.
When you see signs of stress in your fish, you can then take steps to identify the source of that stress and then to resolve it before it becomes a major issue.