Focus on corals, with a few choice small fish.
A pair of small clowns (ocellaris, perc, skunk) a few gobies, or maybe a royal gramma.
For mobile inverts, maybe a pair of cleaner shrimp, up to 5 scarlet reef hermits, 1-2 turbos or 5-10 astrea snails, plus a detritivore kit (or some live sand froma generous reefer) for worms, stars, pods and such. A serpent star would be good, too.
For corals, there are lots of choices. Some of the less obnoxious softies (anthelia, sinularia, capnella), and maybe some zoanthids for a start. Xenia would probably be good as well. The main thing is that you want corals that can tolerate living very close to each other. Toadstool leathers tend to get too big too fast, and star polyps sting their neighbors, and a lot of large-polyped stony corals send out sweeper tentacles. A lot would depend on your lights.
That's the short version.