It's possible that she may think your letter is just one of many. However, because you can generate huge numbers of first letters of impeccable quality we feel they are a big advantage. If your handwriting is very bad we suggest you use a word processor. If your handwriting is very good and you have the time then pick up your pen. Use a nice pen and decent stationery.
Inexpensive sets are available in most card stores.
If your budget permits you can order printed letterheads and envelopes. Use attractive commorative stamps for postage. They don't cost any more than regular stamps and make your delivery more interesting. Don't forget to send all correspondence by Air Mail. I hope my letter finds you wearing that pretty smile I saw in your photo.