As everyone posted, leave your tank without ANY fish for at least 6-8 weeks. My first fish I made the mistake of putting them directly into the tank. Ich followed. One clown died, the other got ich, I transferred it to a QT tank and treated for several weeks, but left it in for about 7 weeks to make sure ich was dead in my main tank. You MUST get a QT and QT all ( no exceptions!!!) new fish for 3-4 weeks. This makes sure you get a chance to see any diseases that may pop up and treat them before you put them in your main tank and lose everything.
When you CAN get started it just depends on what you're looking to have. Damsels are great, but very aggresive. Clowns are a pretty good, hardy fish for the most part to have ( true/ false perc) and maybe more fish later.. very slowly add inverts to the tank ( a ton at ta time they wont have enough to eat) several snails, maybe some hermits, and / or a shrimp or two
good luck! certainly ask if you need help with the ich treatment.
75 Gallon Saltwater Reef
Just your average LVT (licenced vet tech) trying to help the world's animals!!