There are a few threads about this already. If you search, you may find more, and better answers. I'm a woman, and I used to meet guys on the internet sometimes when I was single. I met the first few on Match dot com, two on plenty of fish dot com, and a few more on OKCupid dot com. I greatly preferred OKCupid because the guys there were more like me, but I got really, really lucky on match, and the two that I'm still really close friends with, long after we're all committed to others now, I met on Match. We were just friends with benefits, you know. No strings attached sex, but we'd often take each other when we needed dates for something like a wedding, (and then fuck like rabbits) or just hang out if one of us was bored or lonely. I met the one with whom I had the best sex on Cupid.
As a woman, I can tell you I was contacted a whole lot, but I rarely responded, and even more rarely chose to talk on the phone, and meet. The ones I liked took the time to spell-check and use full words, tried to make me smile, or give me some glimpse of their personality. Even if it was just sex, I wanted the dude to be fun to know. Women have many options, so you have to make yourself stand out. And definitely include photos on your profile. The most important thing since sex was the primary thing, was that I was very attracted.