Do not procrastinate when pests make their first appearance. I'm talking about things like bubble & bryopsis algae, aptasia, blue clove polyps etc. It's so much easier if you address things early.
Get rid of them at the first appearance and stay on it. Don't put somebody else's grungy frag plugs in your tank, get a nutrient control strategy & equipment in place before you need it (because you probably will), remove or kill the organism the day you see it. Do anything you have to to keep pests from spreading. Dip new corals & consider QT for them if you can.