Recommended ways to market a smartphone aoo

Hi

What would be the recommended steps to market a smartphone app?

Or what have you done that has worked for you?

I just uploaded my app to the play store and soon to be on the app store and was thinking of ways that I could market the app.

I know people have done so for free and been successful at it, but I don't even know where to start.

If you tried on reddit, what would be a good subreddit to start at?