Well, i would say to just go to liveaquaria.com or any other site you know of and look in to their sea star pages. I don't have a sea star personally, because those are also animals that need more mature tanks with enough food naturally occurring to keep them alive. So IMO, i would skip out on the sea star for now as well, until the tank is mature. There's a good amount of sea stars out there that can go in a reef tank, so when the time comes, just look around and i guarantee you'll find one that you most certainly like.
I would stay away from coral banded shrimp. I hear they get extremely territorial and kill other inverts and slow, small fish that they can grab. As for crabs.. just look for ones that a reef compatible and you should be fine. Emerald crabs are a great part of my clean up crew, so i would definitely reccomend them to anyone. I have 2 of them and they are just so awesome to watch. Definitely get a cleaner shrimp, or 2.
They are awesome and are also part of your clean up crew if you get them. They're awesome little creatures.
Blood red fire shrimp are also another awesome type of shrimp you can get. Sexy shrimp are really nice too. There are sally lightfoot crabs, pom pom crabs, porcelain crabs.. and all of those are awesome crabs and are reef safe. A general rule i learned is that any crabs that have claws that are black, are ones to stay away from. I would also stay away from the arrow crabs and the anemone crabs, because generally, the arrow crabs are reef safe.. but i know that they like to eat other small inverts. The anemone shrimp are NOT reef safe because of the anemone, and how it can sting anything it sweeps by. I would stay away from those.
And to add to your clean up crew, you definitely need snails. Nerite snails, trochus snails, astreas.. etc.. One snail i would stay away from though are the margarita snails. They are very nice, and do a good clean up crew job, but they are harvested from cold water environments, and are sold to us to put in our tropical saltwater tanks. This temperature change greatly reduces their lifespan. Therefore, you will end up with more dead snails. :/
People also say to get nassarius snails to keep your sandbed clean, but personally is stay away from them because they trashed my tank and killed two fully healthy feather dusters. But just about everyone else i've talked to said their nassa snails just stay in the sandbed. So the choice is fully yours on that one lol. I can't hate those freakin snails anymore than i do now.