How do you decide which features belong in your app's main menu?

Screen space on mobile is pretty limited and trying to show every feature upfront usually makes the interface feel cramped.

We recently simplified our design by keeping only the most used actions visible at all times and putting secondary options inside a slide out drawer.

People seem to find what they need much faster now without the extra clutter.

What is your rule of thumb for keeping mobile navigation clean and easy to use?