Don't send the same letter twice. Girls don't like it.

Make sure you NEVER write to same girl twice. Well... let me take this back. Make sure you never send THE SAME LETTER to same girl twice. It's a very typical situation when a girl is posting her profile again and again after some time period. This happened to me once. I wrote to a girl (and she had a killer picture too, I have no doubts she received hundreds if not thousands of letters) and she never answered to me. Some time later she posted her profile again. The picture and the words were different but I immediately recognized this cutie. I decided to write her again. But this time I came up with completely different letter. Different pictures too. I got a date with her.