Welcome to RS!
The two most important things you need are patience and research. Nothing good happens quickly in a reef tank. Only bad things happen quickly. This is even more true with the smaller tanks since the chemistry can get out of line very quickly.
A protein skimmer is a wonderful addition and IMO one of the most important things to have is a good skimmer. Do not trust your lfs on what a good skimmer is. Very few of them know.
Your other new best friend is water changes. Find a good source of ro/di water and use that for all of your top off water and to mix salt with for your water changes.
Most importantly post pics when you can. We love pics.
