My experience has been this: Guys are very visual so a great picture (but accurate picture) is important. In fact a few pictures that show your face and then full-length that show your figure, well those get a guy going. Also, do NOT post pictures that do not represent how you look now. Nothing worse than going on that first date to only find that the person has gained weight or that they just do not look as good as their pictures. The date will end quickly, perhaps awkwardly, and you will get frustrated. Guys misrepresent themselves too and in the end physical attraction is important as well as honesty so I don't get why people do this.
As far as what your profile says, keep it simple. I found that by putting something simple that represents your personality is the best way to go. I am not a believer of putting your life story down (then what will you have to talk about later) or putting down all the things you expect from the guy. It makes you sound boring or demanding. You can filter through the guys that contact you anyways and you need to spend time getting to know each other through e-mails, calls and dates. Profiles are for getting initial interest not for speeding through the process of learning about each other.