Common mistakes made when designing UI
A common mistake that we make when creating an application or website is that we approach an application as decoration and not design. Design is all about problem solving. The design principles we use in application design is no different than other design principles. A good UI design is based on the same principles as architectural designs or print design. Every color, font and picture are picked for a reason rather than mere decoration. In other words, everything in good design, whether it is in print or application, is chosen to serve a particular purpose.
One of the most common design mistakes we make is looking at a bunch of available themes as a starting point. We can search the internet for hundreds of different templates for web and applications and use that as a starting point for our design. The problem with this is that we are approaching design from a decorator's point of view and not from a problem solving point of view. We don't know what problem the designer of the theme was trying to solve. We don't know why particular colors were chosen or why certain fonts were chosen. What solution may be appropriate for that theme may or may not be the solution to our particular problem. We don't know the why's of the theme.
Another mistake we make is looking at other designs for our inspiration. Again, our problem, and thus our solution may or may not be different from that of the other designers. Every designer faces different problems that they are trying to solve and not all problems are the same. For example, different restaurants have different clientele that they want to attract and designers will come up with different solutions based on the particular problem. This holds true even if the restaurants want to target the same type of customer. Using other designs for inspiration will end up looking like a cookie cutter recipe and will get lost with all the other similar applications or websites.
Looking at current design trends is another mistake designers make when designing an application or website. A good example is Apple's Flat Design. Flat design can cause user confusion because there are no visual cues to whether and item is for interaction. When designing an application or website, we should give clear, visual cues that certain elements on the screen are for user interaction. The user interaction should look familiar to the real world, such as having shadows for buttons. Without visual cues, users may miss out on vital functionality that the application or website provides. The opposite also holds true, if there are user interactions that we don't want the users to interact with without thinking, we may want to make it lost in our application or website so that the user has to deliberately look for the controls.
When designing an application or website, approach it as problem solving rather than art. Websites and applications are meant to be interactive and should involve the user. Everything on the application or website should be deliberate and planned. When it comes to good design, if we don't have a good solution, we don't have a good problem. Matsuo Basho said it best when he said "Do not seek to follow in the footsteps of the wise. Seek what they sought."