Moving from free online project to paid for app, any shared wisdom? (Ie. Stripe Atlas...)

Hello, I am a solo-maker who has taken the gamble of handing in my notice and quitting to build things I believe the world really needs. I'm build www.everyhour.xyz - retrospective a time tracking app, among other things. For this to be sustainable, I need to move to create a business and make my projects chargeable. Do you have any tips, ideas or warnings that I should look into before I jump two footed?! I'm thinking legal worries, suggested software, experiences you have had, or things you thought would be simpler! Honestly anything you wish you had known before. Thanks Alex