wait til your cycle is over before adding any inverts. blue leg hermits are the "nicest" hermits to have, due to their small size. emerald crabs are great algae eaters and help clean up crap in the tank. you will want to add a serpent star as well as multiple varieties of snails. Mexican turbos are algae eating machines and worth adding 1 per 15 gallons of tank water. Good luck
Only add them if you need them. Add a cleaner crew based on your cleaning needs -- do you have algae on the glass, rocks or sand? Do you have detritus building up on the substrate? Add cleaners slowly, or else they'll exhaust their food source and starve to death, and pollute your water with their decaying bodies.
Wait until your cycle is complete (ammonia and nitrite at 0) before adding any inverts.