I wish i knew what has to be more sure about and knew that one thing that wouldn't land me to a place where i'll have to struggle to run my business , i had more knowledge of money control and money management and act accordingly to the budget i had.
Money Management is one of the key thing for someone to have , if you learned how to manage it and manage your credits and debits then you can take your business more forward in the early stage.
Rest i'd say that before entering any business field and any business model just know all about it that what can affect what so you'll be ready for the consequences you'll encounter.