A few things I have learned over the years and in particular launching and growing my latest project[1]:
1) Track everything including errors. Know what users are using and what they aren't. Remove or rebuild less used features.
2) Find out who your users are and what they value. Ignore non-payers.
3) Economize, market, and document features. You not only need to develop and deploy features, but also to price them in appetising business model, market them on social media and SEO and describe/show how to use them.
4) Keep it super simple. You only get the users' attention for a few seconds, use them wisely. Nobody will read long documentation or use illogical/complex UI.
Edit: Why not add some AI features for like pdf.ai? Would make your product more attractive and easier to sell.