Test your water, bring it to the LFS also. Double check to make sure your tank is done cycling. I would start with clowns, they are tough, I had four damsels and they were tough to catch, if everything is ok, and you want clowns to stay for good, then they would be the first to go in. I have a firefish and a klein's butterfly too. Butterflys are tougher, wait on the fish thay are listed as medium difficulty, stick to easy ones. I added a couple of species a week, until I was satisfied. Don't overload things at first, read up.