To start you have to have the correct lighting. What type do you have? You say up and running.. how long has that been? and how are your water perameters? amonia, salinity, alk, nitrate....
As far as care for corals go... those above questions need to be answered to be able to give you advise as to where you are and what you may or may not need to do.
Your lighting will make the difference as to what corals you can have if any. Std Nano Cube PC lights are good for most soft corals. The single best thing you can do for your tank to keep your corals alive and healthy is good water chemistry and frequent water changes to replace trace elements that your corals will need to survive. Some benifit from weekly doses of phyto or zoo plankton... but its not entirely necessary, if you have a coral that is light dependant it will get what it needs from the light and the water column.
Hope this helps