>>1
I probably won't be of much help since, although I've sent messages to girls on dating sites, since all of them were too far away to begin with, I usually stopped trying after a while.

Now my answer: Just ask them to specify things. Like if they say they like a certain author, ask them which books they liked best and why. If they say the like rock, ask them which artists, etc.

This worked for me for a few exchanges... until I didn't feel like bothering with it.

Also say in your profile that you're shy (although, maybe not in that exact way.)

Look at it this way: if you have nothing to talk to her about, then it wouldn't make sense to try and date her. If she doesn't like the fact that you're shy, she wouldn't like it in real life.