Interesting exceptions to the “no netspeak” rule are expressions of amusement. ‘haha’ (45% reply rate) and ‘lol’ (41%) both turned out to be quite good for the sender. This makes a certain sense: people like a sense of humor, and you need to be casual to convey genuine laughter. ‘hehe’ was also a successful word, but much less so (33%). Scientifically, this is because it’s a little evil sounding.

Online Dating Advice: Exactly What To Say In A First Message « OkTrends

True confession time: I used OKCupid this past summer and can’t say enough good things about the experience. Email if you want the gory details but just know that, if you’re considering online dating, I highly recommend it.