Made a ton of mistakes and 'got away' with most of them.
Got my act together in the last year or so when I figured that the more you put in, the more you get out. Also doing things right first time makes all the difference. But I had to do things the wrong way to learn this.
Being a Triton convert I try and keep things in line with their recomendations.
Keeping in line with their recomendations is not as straight forward as Triton make it out to be. You can easily find your self dosing elements that you hadn't previously considered would be part of a healthy reef, but you can often notice the difference.
Once you have Triton all dosed correctly you can see the differnce in your tank. So I recommend it. The tests are worth the money as they can identify problems that you can't or won't test for at home.
I like my nitrate betweem 1ppm & probbaly 3ppm. And Phos as low as poss without stripping it completely. With my stocking though there'll always be a supply.
I like to keep my pH as close to an average of 8.2 as possible. I know you shouldn't chase pH but I like to go with the science, and that shows that pH up to 8.3 encourages coral growth. So I run a fresh air feed from outside, into a CO2 scrubber and then into my skimmer. I want minimal C02 getting introduced into the system. It works well and is cheap to set up.
With different species you're always going to get a little chasing - and thats as far as I like things to go in my tanks.
I probably have more than the generally recommend amount of fish for a 100 gallon tank, but I'm satisfied that they're all happy and that I can maintain their water and look after their future needs. I have moved on fish in the past that outgrew my aquariums. I have no problem with this. I know that when they leave my aquarium they're in great condition and ready for a bigger tank.
The fish are mostly there for my pleasure. I pick them based on suitabilty and comptibility. if they happen to serve a purpose like algae eating/pest eating that's a bonus.
Coral - I live on a small island with very limited options for coral shopping, so I get what I can, when I can. I'm mostly interestd in SPS - keeping that happy is very rewarding.