Awesome. Ill give some basic tips here.
Live sand or Dry sand? If dry you will absolutely want to get some bottled bacteria in there to help the tank cycle (recommend Microbacter7). If you are going reef now is a good time to add your rock. Preferably live, for that tiny of a tank it should be relatively inexpensive and easy to pickup some established live rock from your LFS. You dont need much. 15 lbs should do it.
Although, the stock lighting is only 16w you should be able to get away with most softies and the lower light demanding LPS. I don't think you would get much growth from SPS (though people have claimed to do so) however personally I think maintaining a stable enough environment in tank that small might be tough or cost prohibitive.
Get yourself a decent test kit (hannas, red sea, salifert) and make sure your testing on a regular basis. Ammonia, PH, Nitrate, Nitrite, P04, and if your going to keep coral you will need Calc/Alk tests. You want a good ammonia spike, and drop off. Then once Ammonia, Nitrite are at 0 and Nitrate under 10 you should feed the tank test for ammonia and watch for the drop off back to 0. If you tank does that your ready for livestock I would introduce a clean up crew first. Also I am a firm believer in handling crap before it starts. I would be dosing Vibrant from the start on a new tank to lessen the effects of new tank syndrome ( Diatom/Dino/Cyano) outbreaks.
Personally I would wait until the tank is well established to introduce any corals. 6 Months minimum however in this hobby everyone has different outcomes and circumstances. If your tank is starting to grow coralline algae you should be ready, if not dont worry. Softies might still do just fine at first.
Dont put anything in your tank that you cant test for.
And I will always say to anyone new or experienced. Ease is the key to success in this hobby. Make your life easier and your tank will be more successful 10 fold.
On a nano tank, do not underestimate the power of a water change. If you can do 50% weekly you will be wildly successful. Even 40% or 5 Gallons would be outstanding. Things get out of control quick in a nano, they are tough.
