First.. a mature tank is a MUST.
Second... SPS = stabilty promotes success
Third... everything said above
Last... Patience
Once you understand your tank, do NOT "f" with it! Pick a system and stick with it. DSB, SSB, bare bottom, plenum (now I'm just showing my age), but pick one and then wait for stability before trying SPS. Do your best to ignore the "system du'jour". It a primrose path to hell...:no:
To give you an idea, I run a succesful SPS tank (at least IMO) and I recently tested my tank parameters for the first time in almost three years. Then again, I have been running a SW Tank since '02, first SPS not added until mid '03. I downsized three years ago to a 92 gal to save on electricity. I'm not recommending this, but if you do not understand how to keep a stable system, your SPS WILL die. Even with the best of efforts, you're gonna lose a few along the way. We only THINK we understand reef systems, nature can be a cruel Mother.
Hope this helps and good luck...
This is my current tank, it's a mixed reef with everything from shrooms to LPS to SPS. I like it, you may too...