Designing native mobile applications is a specialized area, and the rules are different than for desktop web design. If you understand these important guidelines, you will stand a better chance of earning higher ratings in the AppStore and Google Play.
1. Understand the Mobile Audience - A mobile user typically needs instant information from wherever they are. Mobile users also tend to be more distracted, as they may be sitting in a bar, a coffee shop or walking to their next meeting. It's important to present only the most critical information so they can get to it quickly and move on.
2. Design for Fat Fingers - Mobile users navigate with their fingers rather than with a mouse. Buttons, icons, menus and other navigational options should be larger so that they can be selected by a user’s finger. Vertical navigation with wider hot spots should be considered over horizontal navigation with narrower hot spots.
3. It's not a Website - Don't think of a mobile app the way you think of a website. The navigational paradigm for a website is "web pages". Mobile apps have screens with functions that dynamically change based on user input. When developing for mobile phones, tuck menus out of the way when possible and make them available by the touch of a menu button or an icon. Tablets provide more screen real estate and therefore may warrant menus that are available all the time, depending of course on the application.
4. Understand the Device Limitations - Don't assume the user will be on a wi-fi network. Keep your interface simple and don't clutter it up with heavy images. It's important that your app loads fast when there is no wi-fi available.
5. Limit the Use of Spinners - Don't go crazy with spinners, you know--those spinning circles that tell your users they have to wait. Mobile users can be very impatient and they don't want to wait. Work with your developer to design a fast performing application, preferably using native code.
6. Analyze Other Apps - Do look at other apps that are available in your industry vertical. How are their apps designed and what can you learn from them?
7 . Don't Reinvent the Wheel - Do follow best practices and don't try to reinvent the wheel. There is some great reference material available from Google at http://developer.android.com/design/index.html and from Apple at https://developer.apple.com/devcenter/ios/checklist/. Check it out.
Thanks for reading and best of luck designing your mobile app.