The secret of mobile app/game success

When it comes to mobile developers and achieving success many don't do anything and are surprised when they don't become overnight millionaires.
They also often don't have a good answer when asked what they've done to try and achieve the success they're after.

Here's the secret to success:

Test. Iterate. Optimise.

Experiment, change things, improve.

It sounds simplistic but it takes time and discipline.
If it was easy, everyone would do it.