Which fish to choose

[MikeP]

Getting ready to add more fish(not right away but sometime soon). My 30 gallon tank is still fairly new but I want to start research now into what fish to get. I have 2 faulse percula clowns and 1 blue damsel (I know it was a bit early, I shouldn't have listened to the guy who sells fish for a living). All three are doing well and I'm keeping a close eye on water quality. Anyway, you know what fish I have and size the tank is. I would like recommendations on what other fish I could get and what I should get for a clean up crew (I have seen banded corel shrimp and they look cool! are they good for clean up?)

Thanks for any info.