What to take care of besides building the product itself?

Hi everyone,

I am developing a mobile application for both Android and IOS. I am planning to launch in June.

Lately I started thinking about what else do I need to take care of beside building, releasing, and marketing the product. I am talking about privacy (user can register in the app), legal matters etc.

For anyone who has experience with releasing mobile applications, what did you do before launching the app?
What do I need to take care of before being able to release the final application?