I see in your profile that you have a chocolate chip starfish. Unfourtunately, these are not reef safe. So they'll probably take a liking to the taste of corals.
A working skimmer can pull down nutrient levels in a tank by removing decaying matter, which can drop your nitrates. The AquaC Remora comes highly recommended. Its a fair chunk of cash, but worth it.
The biggest question when it comes to corals: how much and what kind of light do you have? (and how old are the bulbs)
Do you have sand or crushed coral as substrate?
Zoos (button polyps) are very hardy, and grow fast under the right conditions. Mushrooms as well. Both come in a wide array of colors. Xenia is a fairly hardy set of corals if it has been tank raised (or sitting in your LFSs tank for awhile) - they supposedly don't ship well.
Shrimp such as the skunk cleaner are nice show shrimp. They tend not to hide, and will come up and clean your hand. Hermits and snails are good scavengers to have. I'd add 6-10 blue or scarlet or mexican red hermits.
55g reef, 2x250W 10k MH
+ 2x96W PC
actninc, 10g sump, AquaC Urchin skimmer, 65lbs LR
xenia, mushrooms, wels. open brain, fungia radiata (orange), green eyed zoos
flame angel, mated pair of false perc, 6-line, firefish
20gH electric yellow cichlid