Proper lights, and circulation.
HAve at least 20x turnover in your DT. 50 is the number to shoot for.
MH
LED
T5
For lighting. And in that order for most ideal.
T5 is something people will never agree on. I'm one of those that tells people T5 is doable, but not recommended since your not going to get nearly the growth of LED or MH.
I use LED. Cant beat the color, cant beat the cheap electric bill,and doing bulb changes every 10 years is a big plus.. Corals look absolutely best under LED. However, they don't produce UV light. And prolonged use hasn't been properly documented. People say the colors fade slightly under LED. BUt I don't care since they look so much better to begin with under LED.
MH is the middle one to buy, but most expensive in the long run to operate. Depending on your tank needs, you can have a beefy bill. My 125g cost me $400 a year in bulbs, and $100 in electricity. Figuring $1600 a year to run was a big reason I went to LED.