Do not allow Sawtoothed Calerpa in your tank unless you have a secret desire to kill your corals, or get off on using tweezers.
Do not forget to rinse out hydrometers after use unless you enjoy that panic feeling when it reads .60 .
Do not put away hoses from water changes w/o rinsing them- salt builds up.
Do not dose for anything that you do not test for.
Do not accept that what 'the LFS dude' says is reef law because he wears a funny shirt with a name on it! Do your research!
Do not forget to write down parameters or dosings- memory fails sometimes.
Do not forget that even ' Reef Experts' are not experts on every single facet of Reefing- find at least 3 sources.
Do not believe that you need every new toy or gadget that comes out- people have been doing this for decades without them.
Do not believe for a minute that are reliable shortcuts to nature.