I have learned that just about everyone on this site knows something and nobody knows everything....
Ive learned most about setup and design. No two fishkeepers do things exactly the same way and there's always something to learn from those who may do things differently than you.....reguardless of how much success you think you've had.
I learned that seeing other people do things makes it easier to tell myself 'hey, I could do that'...
Soooo my 36 gallon that I thought was a decent size will be replaced by a 300 gallon shortly. I never would've attempted that without the wealth of knowledge here.