Also, i've also noticed that i seem to have fewere encounters with disease now that my tank is older and more established. I many probs when i first started out, but now have almost none. I jsut get to sit back and enjoy.
When you do get new fish, be picky and be ready to walk out if the fish don't look healthy. Spend some time getting to know the LPS employees to see if they really know their stuff. My current trick is to get them talking about their aquariums or ask them some tricky questions. When you find an employee dreaming of a large tank to put a specific large fish in, you are probably safe. Also, ask about the filtration they have. If the store ahs a UV stearalizer, that means you can buy fish from any tank that is not immediatly sharing water with the one you want.