Research is probably the first thing you will want for your tank. Figure out what you want and go from there. Type of coral what type of fish, if you are going to have messy eater get a bigger clean up crew and go with a better filter. If you want just softies, LPS
with depend on the amount of flow you will need and the lighting.
Patience nothing good happens fast in SW
. You will find the slower you go the more you will enjoy it less problems from the beginning.
Two things I think every saltwater tank needs is a refractometer and a test kit, then a nano tank an ATO I topped of water 2 times a day in my 24 gallon until I got one.
Last but not least plan ahead if you enjoy this tank either you will upgrade or start another one.