Welcome to R2R.
looks like you have a sump with skimmer so you can check that one off
pumps/powerheads
Lights Purchase a desent light or buy once a really good light
ATO
heater
test kit (top three are Hanna checkers, Red Sea, and Sailfet) you will need Ca,Mg,Alk, No3, and Po4 tests. and also ammonia in the beginning
Later
Doser
controller