Aleen Simms has created a guide for developers about to launch an app:
When I started working with independent Mac and iOS developers in 2014 we navigated the maze of preparing for app launches the hard way: digging into the depths of the Internet for guidance, asking other app developers for their lessons learned, and even rushing to fix things after a rejection by Apple. The Field Guide is the product of all of that knowledge, broken up into small, easy-to-understand lessons.
The best part? You can take all the time you would have spent searching the web and fretting over what you might have missed and spend it working on your app instead.
I’m not a developer, but I’ve read through this and it’s great. Go check it out.