I use the following principles to inform my process and decision making when designing products for mobile:
Users are not tied to their desks, and their focus is split with other activities. Information must be current to their location and simple for them to understand on the go, and whilst performing other tasks.
In the case of user who are frequent travellers, users might be checking in, or running through an airport to catch a flight, picking up bags or changing their bookings. They may also be lost or in unfamiliar surroundings.
Design For Interruption
Mobile usage tends to take place in much shorter bursts and the user is much more likely to be interrupted – either in real life, or from within the phone itself. Ensure users can start and finish tasks quickly, abandon partially completed tasks and resume them later.
On average mobile users spend less than one minute using any one app. User experience and functionality need to be designed to support and enhance these quick in-and-out interactions.
Users need immediate feedback for their interaction, even if the resulting operation/result takes longer, let them know it is on its way. Provide clear, appropriate and immediate feedback for every user action. Use visual highlights, transitions or animations. It should always be clear to the user whether their task was completed successfully or not, e.g. via a prompt, or focusing on an item that has just been created or saved.
More than 0.5 seconds, provide the user with an on-screen indication that something is happening.
More than 2 seconds, an animation or progress bar should be displayed. Also consider that most mobile users are paying for their data by the GB.
Design For Thumbs
On smartphones, people use thumbs more than fingers, in fact, users with a bag or other item in their hand will be using a device with one hand, navigation is then exclusively using the thumb. Even two handed operation including typing uses mainly thumbs. Consider the proliferation of screen sizes, larger screens posing reachability issues for principal navigation.
Harness Native Features
Capture more than just touch input. Things like sound, movement, location, proximity and more, can now be easily captured by mobile devices.
Think about how you can improve your user experience with intelligent use of it; using data the user didn’t even realise they were giving out is a great way to create surprising, memorable and catpivating outcomes..
People interact directly with content using touchscreens, rather than abstractions such as a mouse or keyboard. Leverage intuitive touch UI by minimising interface chrome (buttons, tab bars, checkboxes, sliders etc) wherever possible and putting content front and centre. Content is king.
Mobile devices have two orientations: landscape and portrait. Portrait is by far the most popular orientation, so design for that, only use a landscape orientation if it adds value to that point of the experience (adding more rows to a table of search results) or is a screen that requires a lot of typing.
Never use gestures for core navigation or features of an app, they are invisible so the user does not know they are there. Gestures should only be used for advanced features not crucial to the core experience.
These behaviors are why people pull out their mobile devices. Design and organize your experience around their needs.
(urgent info, local)
It has to look good. Spend time on the details. Due to the personal connection to phones, small defects start to annoy users. This is further exascerbated by high pixel densities of mobile devices, and the attention to detail demanded by smartphone savvy users. Don’t forget the little things.