Being bootstrapped means that you need to do a lot of things by yourself. You can't hire a team yet because of the lack of money and at first, everything is manual until you identify repeatable patterns that you can automate.

With https://pdfshift.io, I'm in the same situation. As a tool to convert HTML to PDF, I get many requests about documents not being rendered well on PDF. I take the time to help my users tweaking the CSS to have the perfect result. This takes a lot of time and doesn't always make them convert, but for those who do, I have a lower chance they churn because they know they can count on me.