Utility
The service should be used immediately. Instant gratification, remember? Users should be able to start using the app as soon as they download it. If they have to spend too much time setting up your app, importing contacts, signing in, or creating an account before they can actually try it, you risk losing them at a very early stage.
Cleaning
Users need to know what to do right bw lists away. Design plays a key role in the usability of your app, which will ultimately impact its popularity and success. Use large fonts and plenty of white space to make your app as clean as possible, and try not to present too many features at once on each page.
Simplicity
Simplicity is the starting point for any high-performance service that can grow and expand over time. This is especially true for companies launching their app on marketplaces. The advice is to start by doing one thing really well and add more features only when you are successful.