Brackish fish, stay or go?

Hi everyone---I'm new and have had my tank cycling and solid for nearly 7 weeks- it's a 90 with 3 large canister filters on it. I cycled with six mollies and they are all doing well, I also grabbed 2 small green scats, a mono, 2 small black tip shark cats from my brackish too.... lastly, I have a scooter "blenny" (I learned it's not a blenny at all apparently) and a Firefish.. then some inverts.. so....I'm ready for some 'real' marine fish with the colors that come with them and need to know what can/should stay and what I can return or put in the brackish tank...everyone has been doing well together without incident for about three weeks..... So...what should stay, go and what wonderful colorful and peaceful beauties can I start to add and in what order... Thanks and looking forward to responses and wisdom... Dave