The mobile platform for earning is quite hard, but I'm not here to be a pessimist. I suggest sticking to making your game good, beautiful, and memorable. Along with that, there should be IAP. Ads are an overall nuisance, and as someone that hated ads when they played mobile apps like crazy years ago, I just don't think ads are a overall good experience for the player, even if there is an option to remove them.
As for IAP, be sensible and be smart.
Risk Rocket now available on Google Play