Here is what order of things I treat as most important in keeping SPS.
1. Perfect Water
2. Flow - Very High flow.
4. Parasite/Predator mitigation
And you will be successful.
+1 I also agree with Michelle. Start with a monti cap as a beginner SPS coral prior to placing any acropora in your tank. You have quite a few options with caps. From the cheap orange cap (Free in some cases) all the way up to the Reef Raft Pink/Orange/ with blue-ish polyps cap ($100 per 1")
To ensure perfect water, your very first step should be to pick up some test kits. You will need to ensure you have low levels of Nitrate and Phosphate. You will also need to test your Ca, Mg, and Alk levels.
Strong flow, but not direct. Too much strong flow can cause slow tissue recession and stunted growth.
With an HQI MH, you should have sufficient lighting.
Perform some research on Coral Dips. I use Coral Rx, but some folks swear by the new Bayer approach.