How/where/when to pay taxes
I started as a freelancer, right out the gates. And nobody told me that, hey, you have to work out your own taxes as a freelancer. I knew nothing of freelance tax obligations. Nobody told me that I needed to make a point to send a portion of my paycheck to a savings account, where it would sit and wait to be given to the IRS, every fiscal quarter. I was just spending money, forgot nobody took out my taxes, and faced a huge bill from the IRS. I also didn’t know about many of the deductions I could have reported.