The first thing that should be on your mind when writing a message to someone you meet on an online dating site is improving your communication skills. That may mean trying your hand (at writing, this time!) and also knowing some little secrets that can improve your communication.
First, try to be original and creative. Avoid cliches. Think in advance of original sweet phrases and write them down, so you don't forget them by the time you receive your first email response.
Second, ask questions. Not too many at once, but never send an email without asking a question. And for the beauty of the game, try avoiding closed questions(that can be answered by yes/no.) Sometimes, put yourself in her place, give your own answer to the questions you ask her, and send it along. You'll be surprised of the effects.
Third, have structure (great title/beginning, colourful body, and great ending.)
Try it. And get back to me strutting your results.