1. Be aware of the intimate relationship users have with their phone
People are usually not comfortable when it comes to sharing their phones with others. They will either hold their phone to show it to you or will panic if you have their phone for long time. It is different when it comes to sharing tablets or laptops. Developers should keep this in mind when designing apps for mobile phones as compared to apps for tablets.
2. Assume users want privacy & ownership
Give users the freedom to control their privacy so they are more confident in using your app.
3. Make things as easy as possible
Keep in mind while developing your app, to make things as easy as possible and to keep the number of links to a minimum. You should always try to keep things simple so that users don’t have to do a lot of work. There are, however, exceptions to this. Example: Payment services should always be a slightly difficult process for the user. It makes the user more comfortable using your app. You can setup your app to require passwords or other authentications before processing any form of payments.
4. Screen Size implies’ users state
There are more chances of a user watching an entire movie on a laptop than on a tablet or a smart phone. Another thing to keep in mind is what else you might add in your app to make users more engaged depending on the device they use. Similarly, a user might use a smart phone for light work like looking at a spreadsheet (usually not editing) but he/she might use a tablet or a laptop for editing a spreadsheet or creating pie charts. Users might also use a smart phone for features like calling, texting or IMing while he/she usually won’t use a tablet or a laptop for it.
Source: Mobile March 2013