I don't remember now if I mentioned -- I was on OKC but deleted my profile a couple of months ago. I've gotten into a wonderful primary relationship and for someone like me it's too easy to spend a lot of time playing around online. Plus once I started with LJ I decided to send my subconscious a message: "stop looking for possibilities and explore this wonderful woman instead."
But based on my experience OKC is most successful for guys if they use it well -- that is, write an honest and fun-to-read profile, do some journaling (unlike in your profile, in the journal you can post pics of your vacation or pets or whatever) and also comment on other peoples' journal entries, use the chat feature.
In other words, it seems to work best to be visible, to put yourself out there as an active and interesting member of the OKC community. I had a lot of fun and chatted with some wonderful women, a few of whom I still talk to now and then.
Things women in particular should know: you can block both messages and chat from specific users. There are some men who are offensive idiots and you can and should block such people the very instant they bother you. There are also scammers, both male and female, who will appear very attractive but who will end up asking you for money under various pretexts.
Overall it was a really positive experience for me, though. Have fun!