Guidelines for writing appreciation letters: State what you appreciate and briefly explain why. Giving a letter of thankfulness is one of the best ways to express gratitude to someone.Here are the appreciation letters that you can download for free. I want to convey my heartfelt gratitude to all the members of the foundation who work tirelessly to make the world a better place for individuals like me. 1. Open with a salutation. Express gratitude in a heartfelt way. Send a note using Canva's free and customizable thank you letter samples. Thanking your volunteers is essential to building lasting relationships with them. Here are some tips for how to write a good volunteer thank you letter. The message of appreciation should stand alone.