“It only takes 5 users to discover over 85% of usability problems.”
Usability means, in the most simple understanding, that users can use an application easily for its intended purpose. However, problems with usability are one of the biggest reasons users don’t enjoy using an app and as a result of this many don’t become returning users.
Luckily for app developers, it only takes 5 fresh pairs of eyes to discover most of these issues:
A good strategy for testing is going to a popular café and asking people to test your application for 10 minutes. Let them test the app and observe their reactions. After 50 minutes of testing by 5 different people, you should start seeing patterns in the results. Once the development team have analysed the problems from the feedback, you can return to the cafe and perform the testing again. Hopefully you will see that the initial problems were adequately addressed (and if any new ones arose).
This great video explains this, and offers an in-depth app testing tips: