Make routines sing
Make the experience smooth and effortless from start to finish. Clear away every obstacle and make your application smarter and repetitive actions faster. Anticipate each move and efficiently adapt to each response.

We're all different. Some people use their BlackBerry smartphone mostly for calls, others never leave BBM, and some are all about games. But no matter what people do, try to make your application smarter and repetitive actions faster by adapting to individual usage patterns.
Consider auto-completion of email addresses. Most algorithms use a combination of frequency and recency to prompt the most likely recipient of an email. You could try the same context-sensitive approach in your application. For example, if someone emails Leticia and Julie together more often than they do separately, why not provide an alternative to select both on one tap?
The first time that people do something it's ok if a few more steps are required. But when they do the same thing a couple of times, the usage patterns become more obvious. Your application should identify the usage patterns and the interface should adapt accordingly.
Here are some other examples: