I am not a good writer, so I will write my comments as if this were you. This is standard stuff you already know. Be honest, be factual, and give them a good reason why you should not be dismissed and offer them data as to what you are doing to correct and not repeat the situation. For example if there are poor grades, what is being done to improve and maintain your grades. If this is for academic dishonesty, you need to accept responsibility for your actions and what you are doing to preclude a repeat of the situation. Apologize and be humble. I assume you may be also be presenting your appeal to representatives of the school in sort of an interview format. If that is the case, have several of your classmates or friends conduct several mock interviews. Have them be tough but fair with you to get you accustomed to what you may hear and how you will respond. Do not be angry, do not cry; maintain your composure. Be professional and after all is said and done, thank them for giving you an opportunity to address the reasons and solutions for the dismissal. People make mistakes and errors in judgement all the time, you just have to convince them there will not be a repeat. You have a shot of being "forgiven" once, but not twice. Do what you have to do. I wish you well and good luck!!