I'm not so sure on the revenue part as I've never done that myself.

But the easiest ways to get started with promotion are:

1. ASO
2. PR. (you can do some of this yourself. Naturally, helps if your app solves a new or interesting problem).
3. SEO (easier if it's a niche app).
4. Paid social ads. I'd start with Twitter and Facebook (though you might want to add inInstagram or Pinterest depending on your app).
5. Recruit plenty of paid product testers now. Get their support/feedback to help build the app. Make them part of the process and then they will probably help spread word of your app on launch day.

Good luck with your app!