I am still in the processing of building out my side project. What has helped me the most is only building what the customer is willing to pay for. That means

I am still in the processing of building out my side project. What has helped me the most is only building what the customer is willing to pay for. That means going out and talking to customers, finding out their problems without suggesting your app. If your app solves their problem, ask them for a commitment to buy. The next best thing that has helped me is to document and automate as much of the system as possible. This includes the server setup etc. If you need to upgrade to a new version of the database or the OS, how easy is that for you in your current process? If you do not automate something, did you document it well enough the first time so you can easily perform the task in short order without having to scour the internet for answers?