• Simple: Visually approachable. Thematically obvious. Uncluttered. Clean.
• Memorable: Distinct. Unexpected. Sticky.
• Timeless: Don’t follow the leader. Don’t get on the arc. Design for forever.
• Versatile: CMYK, RGB, GREY, B&W, OK.
• Appropriate: Culturally and contextually appropriate. Convey emotions and ideas in ways people understand.

These things are not hard to do. They just take a little time and thought. The difference is both obvious and non-obvious in the look and feel of a thing.

Finally, these are guidelines. Once you understand how to follow them you can start to understand how to break them.