Hello and welcome aboard. Unfortunately a lot of learning is the "Hard way." Trial and error, but by studying, and interaction,(Asking lots of questions from experienced keepers) a lot of the error portion can be eliminated.
Sometimes just plain old common sense is a big factor. A good friend of mine once told me that common sense ain't so common.
The more I look around, the more I fear she may be right.
That being said... you've come to a real good place to ask questions! I hope you enjoy your stay, and stay a long time.