Simplify to the point that the application almost looks "simplistic" ... almost like there’s not too much to the application itself. This makes the application less intimidating to users, especially to new users.
With this approach, you may not win any awards for elaborate, colorful, eventful looking user interfaces, but your users will find your application to be intuitive, easy-to-use and inviting. The learning curve will be dramatically reduced. Users will jump on board quicker, use your application more frequently, and get more value from it.