Here are three reminders that are not emphasized enough in my opinion:
- When possible, design for mobile first since the mobile environment offers the most constraints both real estate-wise and feature-wise.
- Make sure to identify the users' goals for each separate type of device (tablet versus smartphone versus PC, etc). The user's primary and secondary goals depend on the context of use of each device and therefor the users' goals need to be defined for each type of device. You might be surprised at what you discover!
- Design low detail wireframes then high detail wireframes followed by visual design mockups scaled to each screen size and containing the essential elements common across all devices types. This helps to create unity across devices in the early stages of design.
- Establish and document design style guidelines and patterns noting the specifications for each device type when the design differs because of constraints.
In addition to other tips, the article also includes a table comparing native mobile apps to mobile web apps. Check it out!