Writing a sincere thank you note is one of the professional skills that can make a lasting favorable impression. People like being appreciated. One of Dale Carnegie’s fundamental human relation principles is “Give honest, sincere appreciation.” When writing a thank you note, use a plain, small card. However, the card is not as important as the effort, so if paper is all that is available, write the note anyway! Use this 6-step formula as a sure-fire method of expressing appreciation in a written note.