Biggest Mistake

This has probably been asked before so forgive me if I'm being redundant. I launched my business in February and have been trying to do it on the side until I can sprout a couple roots but along the way I am finding it more and more difficult to work FT for someone else and try to run a business. That isn't really the point of this post, I am just trying to establish I haven't had much time to see my mistakes. So my questions is this, when you started your business what are a couple of the biggest mistakes you made? How did you overcome them?

Thank you