Prevent overdraws. Know your cash balance at all times, less outstanding checks and expenses.

I see business owners manage cash from bank accounts all the time, but it's the fastest way to overdrawing. Your bank account balance doesn't know what checks you've written or what will be auto-debited at any second. Manage cash from a real, grounded place. Estimates are fine. I ballpark every day. But I always know about how much I have in my account to make sure I don't spend money I don't have. 

So keep a register, even if it's paper and prevent all the overdraws. Save those $25 dings for an extra investment in your Acorns account.