Help needed: First messages over text / online messaging

So this is a major sticking point for me, a lot of the time I'll get a girl's number or message on an online dating site and she'll either never respond or she only sends a few responses, then it's silence. I get the feeling that I'm being to boring/nice or whatever. So I'm just wondering what are some good examples of introductory text and online messages and the things that I should keep in mind when messaging new girls.

Thanks

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