Lc4lyf

Hi folks! I'm a current graduate student and my former labmate and I are nominating our graduate mentor (a professor) for an "excellence in graduate mentoring" award. We're both required to write a letter of nomination for him and the only guidelines for the letter are "specific examples of exceptional mentoring and impact on the student". I have my specific samples listed and I am truly grateful for the work he put into me and my future. But I have never written a nomination or recommendation letter before, or even seen the letters written for me for various applications. I have no idea what the tone or format should be. Does anyone have any tips or examples they'd be willing to share with me? Thank you!