Clowns are a damsle so the more meaner clowns (clarki, maroon, tomato) should be introduced towards to the end of the list so there bottom of the totume and have to work there way up. If you put something like a maroon clown in first he sets his territory and then when something new comes in the tank he will try to kill it because its in his territory. Also when adding fish try adding 2 at a time (if that type of fish allows it without going over the bio load) When chasing one fish it gives the other a chance to rest and vise versa.
But if you truely want a docile first fish and something that moves around I would get a cardinal. If you want a docile fish and something that moves but not as a mutch the gobie or blennies are a good way to go.