It seems that a lot of people don't seem to be getting any replies from people on these types of sites. So, here's a little guide:

1 - Read the person's profile, and see if you can find something you may have in common.
This can be anything from a band/music type, a sport you both like, a language you both speak - anything. Base a message around it if you can.

2 - Do not type a short message that just says 'Hi, want to chat' or something along those lines.
Show some imagination. People get a fair few of those messages every single day. If they don't reply to others like that, do you honestly think they will reply to you? EXACTLY.

3 - Don't give your email address out in the first message
It makes you appear to be desperate. That is never good. Send a few messages first, then give/ask for email later.

4 - If they don't reply - Don't send them more messages
Wait a couple of days to see if they respond. If not, they just aren't interested. This does not mean you should flood their inbox with 100 messages until they reply.

5 - Don't be too serious
Say something amusing. Not stupid amusing, fun amusing.

6 - No chat up lines
I don't think this one needs an explaination!!

Ok. Finished. Feel free to add anything to this.

Cheers...I suppose that must apply to me as I haven't really started messaging any females yet

That's excellent Laura. The next time i get some oik asking me "wanna chat?", I'll send them that list!! lol