When designing interfaces for mobile devices you should have a couple of things in mind: users, their mobile devices and the way they interact with them. User-centric design is important here. What if some of your users have large or small hands? What are their cultural and religious norms? How are they interacting with their devices now and what are they used to? These questions should always be in the back of your mind when doing UX for mobile devices.
We should aim to simplify the experience because of the strictness of the mobile devices screens and/or UI’s. Often, users have only a couple of inches to work with on their tablets or phones, and especially if we are talking about devices like smartwatches. Big, simple designs that are simple and concrete do the trick here.
Always have in mind cross-platform transitions and individual users’ capabilities but also disabilities. Your designs should work with just about anyone even if they are not professionals in using the devices, or if their level of usage is somehow impaired by their disabilities. Your designs should also work seamlessly with existing screens and devices, but also should be easily adaptable for future updates.