Imagine, for instance, that you were asked to create an application for completing insurance forms. A natural reaction would be to design an interface that exactly duplicates the paper form on screen. By creating logical groupings of fields from the original form and using a tabbed interface or several linked forms, you can present all of the information without requiring the user to scroll. You can also use additional controls, such as a list box pre-loaded with choices, which reduce the amount of typing required of the user. You can also simplify many applications by taking infrequently used functions and moving them to their own forms.
Wizards can also help to simplify complex or infrequent tasks.
The best test of simplicity is to observe your application in use. If a typical user can't immediately accomplish a desired task without assistance, a redesign may be in order. The use of color in your interface can add visual appeal, but it's easy to overuse it. With many displays capable of displaying millions of colors, it's tempting to use them all. Color, like the other basic design principles, can be problematic if not carefully considered in your initial design.