The usability of look and feel

Frank Spillers on Demystifying Usability says, "Balancing good visual design with usability is challenging, though not impossible." He offers the following Usability Guidelines for Graphic Elements:

Use of graphical elements generally
Images should have a connection with the audience
Avoid clip-art (excellent advice, in my opinion!)
Icons should be intuitive, crisp and used strategically (not randomly)
Branding elements should be clear and distinct and follow company branding guidelines.
Use graphic design to enhance visual appeal
Be sensible about minimalism

For more details visit Demystifying Usability. Spiller provides monthly posts on a wide range of usability and user centered design topics.