Great question! Facebook is a good start since you can target your audience and measure your results.

Since you recently launched your app, I'd recommend a mini-launch campaign around it. You can put together a variety of marketing tactics that all work together to spread the word about your new app.

For example, reaching out to app review websites, sending a press release, working on your App Store Optimization, and more.

Would be glad to talk any time and explain more.