Let people scroll: Most websites take care to display the most important information in the top half of the page where it is seen first (“above the fold”), because people sometimes leave a page when they don’t find what they’re looking for near the top. But on iOS-based devices, scrolling is an easy, expected part of the experience. If you reduce font size or squeeze controls to fit your content into the space of a single device screen, you’re likely to end up with unreadable content and an unusable layout.
Focus your app: Websites often greet visitors with a large number of tasks and options from which they can choose, but this type of experience does not translate well to iOS apps. iOS users expect an app to do what it advertises, and they want to see useful content immediately. The above guidelines are from the iOS Human Interface Guide.
Some other guidelines I follow are
Use Content for navigation : Downplay application UI so that the focus is on content; present content in beautiful ways. Let's users touch the content and interact with it. I'll add more in the coming days and weeks...