We all make mistakes. Here are mine so far, hopefully these will save you valuable time and money.
The biggest error so far has been the complete lack of writing everything down on good old fashioned pen and paper. I have lost so much time as my brain isn’t as powerful at remembering ideas, passwords, or even website addresses. I quickly grabbed one of these and fixed the problem. The bottom line is you have to be organized. It will save you more than you can imagine.