I ask people to support me by becoming my patron on Patreon as Menu item. Right now it brings me 11$/month (https://www.patreon.com/hovancik) and it goes up and down. I could do better by engaging more with people, I guess (in past some people donated when I fixed their issue very quickly).
Over time, some people also donated on paypal (5-15$ a time).
I am thinking to add "premium" features: users can access them after auth via patreon or github (if they contributed).
Premium features will be just some sugar, nothing that normal user could not do.
I also have newsletter where I try to bring some app related stuff that people might enjoy.
some tips:
- watch for mentions of your app on social media and interact
- ask for support, if people like your app they will help
- being open-source also helps