The following are the things to keep in mind when writing an immediate resignation letter: Write the date first. Explain only necessities.To write a short notice resignation letter, include your position and effective date, explain your reason and express gratitude. Explore why a good resignation letter is important and how to write it, and check out our free resignation letter examples. How to write a short resignation letter? How to Write this Resignation Letter: Expert Tips and Guidelines. There are several reasons associated with family which may compel your resignation. Mention your intent to resign and the position you're leaving. I have decided to resign due to personal reasons that require my immediate attention. Individuals are urged to consult legal counsel of their choice.