I am still new but I can put up a list of things that I have learned/used to help stave off a failure (for now).
1. Patience- don't rush into a build, purchase, treatment or rescue.
2. Do what your tank wants, not what you want- don't buy the fish/coral/anemone you want, buy the fish that works for your tank.
3. Set aside the time- don't do anything if it's rushed. Pick a date/time to tinker or set up equipment, dose, monitor, acclimate and so on. These things all require time and if you're not invested, it will show.
4. Chemistry- know what chemistry your water is at all times. If you dose manually , start small, record the effect, make adjustments, test often.
5. Don't dabble in equipment that you are not ready for- don't know how to plumb an ATO? Then maybe you shouldn't. Not saying you can't have an ATO but maybe something more simple. I use a gravity fed ATO. More work but less risk.
6. Pay close attention- if you don't have a good memory keep a journal. It will help you figure out what is happening by identifying actions that lead you there. Example; coral bleaching- did you touch the light setting, dose, add livestock? Being aware and keeping track go hand in hand.
7. Quarantine(debatable)- I prefer it but it is optional.
8.Alert system- $200 piece of mind (again, optional but I prefer one)
9. Listen- take the information with a grain of salt but most experienced reefers know how to avoid mistakes. Plus, a fellow reefer will honestly tell you a blue hippo tang is too small for you 60 gallon because he has no investment in seeing you buy the fish. Others may claim it's possible but results are anecdotal and sometimes lucky, stick with the honest answers.
Anyone else can add to this or deduct but I feel it is a good start to keeping a long lasting system.
A generator is handy too, just make sure it starts when you need it.
10. Study chemistry (as per reefers needs...) so you can really understand what's happening and recognize misleading information. Ask/challenge Randy Holmes-Farley directly when you have a doubt. Even if you think it's a "dumb" question.
11. Never, but NEVER make changes or connect/disconnect anything before leaving home (even if it's just for dinner)