I'm going to echo what's already been said...
Take your time, make sure your tank has the right flow/lighting for what you're trying to grow, take your time, read, keep your tank as stable as possible.
I've had the best results with regular water changes, using Kalkwasser in my topoff water, and employing a good skimmer and lights. When you're adding new coral to your tank it's more important to consider the coral's needs and where the best spot is in your tank for it, rather than picking a spot that's pretty and re-adjusting your tank systems (pumps, lights). Oh, and do lots of reading. And, when you put corals in your tank take some time to watch them and verify that they're "happy" where you put them.