The Wrong Photo
Your photo gives people a few clues to you and your personality so it's vital that you get it right. On a professional site like LinkedIn it is important to present a professional front, so please, no family shots. Save those for Facebook.
A recent head and shoulders shot, perhaps at work, helps people connect with you. I've seen some profile photos that have gimmicky effects, this is a no-no. I also think you should stay away from cartoons of yourself, company logos and images of the product you sell.
But the worst crime of all is no photo at all. To me that just says that you can't be bothered and aren't really taking networking seriously.
