Although pictures are important, I guess the most important thing in a profile is the content. If you have great pictures, but don't have enough content, you're going to look like a fake. And nobody wants that.

But again, that's just my very personal opinion.

It's not just what the picture is of, (no dick pics, as echoed below) but a nice clear picture depicting who you are. Smile and be genuine. Self pics with the outstretched hand and surprised look, usually looking up the nostrils or something, should be avoided. Take some time and take a nice one, grab a tripod and have some lighting.

Exactly, des. Smile, eyes, face. No clutter, dirty or clean laundry, or toilets in bathroom mirror pics, please!

Use ones that show you in a way you want to represent yourself and at your best. Smile, suit, shorts, bathing suit etc. Leave out the dick pics every guy has one and it screams I'm stupid and think that is all a woman wants.