Basic Tank Advice wanted

Hello everyone! I am new to the saltwater tank hobby. I currently have a 30 gallon tank with a canister filter, no sump. I have a fairly strong current and good lighting(don't know the specifics). I have a Coral Beauty, a fire shrimp, a goby, a emerald crab, two mushrooms, a trumpet coral, and several hermit crabs and snails including a conch snail.

I am just wondering any good tips on cleaning, water changes, feedings, filter cleaning, SAND CLEANING(basically dont know anything on this), and any other tips and advice. Including what fish to add next.