I've read some good advice here, but finding a decent source for the corals has been most important for me. Having found that source, and educating myself about all corals I buy, I've had a great deal of luck with them since I got started six months ago.
And the great thing is that you can always trade them with other hobbyists and propagate them for trade-ins at your LFS. Not to mention that I haven't yet heard of a maximum coral limit for a tank like you have with fish.
One thing I've learned for certain: if the knowledgeable folks/literature say it's not for your tank (i.e. it needs MH and you've got PC's), don't buy it.
Good luck!
:happyfish