a mature tank,good random flow,quality lighting ATI ect,stable water parameters,dont put your hands in the tank too much and
handle corals as less as possible,dose mag,cal,kh at natural lvls with fluctuations kept to an absolute minimum.
another method is keep up large water changes weekly and only dose if sps get so outta control that water changes cant keep up.
proper phosphate control and start tank with aqua cultured LR or dead rock and seed the rock and make double sure
that any corals you put in the main display are free from any kind of nastie unwanted algae that could become a problem once
it gets a foot hold or any other undesirable for that matter,go slow and watch it grow,dont cut corners and buy quality the first time.