I love graphs and OKCupid just did this really cool blog post full of 'em. They say that on average 32% of messages that people send out get replied to. So they looked at specific words in a first message and tried to figure out what made people more or less likely to respond. Here's one graph, where 32% is the baseline.
The post also has what words are successful (number 1 on one graph: band). Check it out
http://blog.okcupid.com/index.php/online-dating-advice-exactly-what-to-say-in-a-first-message/
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