A summary of https://www.thinkwithgoogle.com/collections/principles-of-mobile-app-design-engage-users-and-drive-conversions.html
Engage users by addressing their tasks clearly, placing calls to action up front and center. Highlight your app’s key and new features in context at the appropriate place in the app.
Example: product categories in a menu “Product categories” should not overlap.
If you have steps, and user goes back, then he should go only one step back, don't jump to the top.
If app is using the GPS location, then it should be possible to change location manually too.
If you have app and mobile website, then they should use the same design/navigation concept etc.