You need to learn ASO to optimize the app listing in this order of importance: Title, sub-title, description, then pics.
If you have some money to invest, start a campaign on FB Ads to get some installs and get some real ratings from users. You also can get the "blackhat" way and purchase some ratings and comments to boost your app, please be careful doing this way because Google can catch you very easy and punish your app.
I has an idea some years ago about a picture app and it's get a broadcast when the user take's a pic and show a notification inviting the user to optimize the recently taken picture, this way the user always will remember your app. I don't know if it it's possible with new Android apis.
Good luck