This comes from Margaret Shepherd, author of the book "The Art of The Personal Letter." Here's what she says:
Rule #1 Avoid starting with "Thank You".
I am guilty of this, big time! But every time I start with "Thank You" it feels like I've gotten to the punchline prematurely! :) Ms. Shepherd also suggests that this shows a lack of imagination. (Booo....) So let's not let Ms. Shepherd (or your recipient) think for a moment that you lack imagination! Instead, before you sit down to write, get creative about how you'll begin.
Rule #2 Instead, begin with "You".
Rule #3 Acknowledge the relationship that you have with the recipient.
I like to recall special memories that I have of that person or moments that we've shared.
Rule #4 Use conversational language.
Of course, this will depend on the degree of formality of your relationship. Remember you can be fairly formal and still show a lot of personality in your writing. A thank you note, by definition is personal, so be yourself.
Rule #5 Be specific about what you are thanking them for.
For instance, if you are thanking a teacher for helping you to develop a specific skill or character trait, give them examples of how you've used that in your professional or personal life. If you are thanking them for thinking of you or serving you in some way, let them know how their service made you feel. Be descriptive, specific, and focus your compliments on them.
Rule #6 Offer up compliments that you have received from others about the gift they've given you or share examples of the positive ways you've been affected by their kindness.
People like to hear great anecdotes. These will be the parts of your letter that people will most likely remember, cherish, and re-read long after the note is originally received.
Rule #7 Begin and end on a positive note.
This is a no-brainer. Be positive. Be delightful and delighted, and express the joy that their influence on you has brought to your life. I like to share a quick quip or repeat something that the recipient of my letter is known for saying, or that remind them of an "inside joke" that we share.
I wanted to share this great information because I love the idea of Thank You notes but I hate my hand writing, so right off the bat I find it difficult to start. Then knowing how to convey what I want to say is another issue. I love getting Thank you notes and have saved most of them I have ever gotten. Some people are so good about writing them, I want to be better at writing and sending them. There are so many amazing people in my life I want express my gratitude to.