1
Gathering Information
Before writing your demand letter, it is important first to gather your thoughts and consider how you have been wronged. Attorneys will remember the basic elements of a cause of action from their law school studies. Pro per clients (who represent themselves) may not understand the elements of their action and their significance, but it is still important to pause and make a list of the events and actions that have occurred in your case. For instance, enumerate all of the correspondence and interaction that you had with the other party that resulted in your dispute. Note what was said, by whom, and in what context. Once you have the facts settled in your mind, you can proceed to the next step. Write an introduction to your letter stating your reason for writing, e.g. "I am writing this letter to explain the circumstances of our interaction and why I feel the need for reimbursement." Take a neutral tone and avoid antagonistic statements like "Give me my money, you bum!"
2
Voicing Your Grievances
Next lay out the reasons you feel justify your position. For instance: 1) I offered to purchase your car for $5000 and paid you a $500 deposit. 2) You accepted my offer and told me you would deliver the car to me on Friday. 3) You sold the car to Fred on Thursday and never delivered it to me as promised. 4) You refused to return my purchase deposit when I asked for it back. It is important to explain why it is necessary to reach the conclusion that you have. Remember that it is important not to jump to a legal conclusion without supporting it with facts and viewpoints, e.g. "By refusing to return my money, you breached our contract and broke the law."
3
Making Your Demands
You also need to clearly state your demands so the other party understand what you want, e.g. "Accordingly, I want you to return my $500 deposit."
4
Allowing for Compromise
Sometimes, legal issues can be kept out of court if you make an offer of compromise. Court is expensive and most times you really don't want to have to go to court. After all, you might lose. Try making an offer to the other party that gives them an out without necessarily admitting fault, e.g. "I understand that you are in a tough financial situation and may not have my money available to return, but I am willing to take something else in return. I really liked the hubcaps you also advertised for sale with the car. If they are still available, I will gladly take them instead."
5
Standing Firm
Remember though that this is a "Demand" Letter. As I said, don't be rude, but know when to stand firm. Don't give too much wiggle room for the other party if you truly feel they are wrong and trying to take advantage of you. Stick to the facts and make your position clear. If they violated the law, call them on it. Tell them this is their opportunity to fix the problem and make it go away before the court gets involved and they lost their shirt. "Please understand that what you did was a violation of the Criminal Code section 3456.56 (stealing earnest money deposits). While I wish to resolve this matter amicably, I will sue you in small claims court if you do not work with me. If this matter goes to court, you will most certainly lose."
6
Giving Notice
Don't forget the notice at the end of the letter! A key component to the demand letter is letting the other party know that they have a finite amount of time to respond before you resort to legal action. This is crucial in many jurisdictions! Some require 30 days notice, some 60, some 90 days! Look up your statutes to see what is required. Make sure you mail the letter Certified Mail with a Return Receipt Request so that you can prove that the other party received your letter before you went to court.
7
Taking Action
Now that you've sent your letter, be ready to follow through on your demands. Remember, don't be afraid. Most people count on other folks' hesitance to go to court and may ignore your letter entirely, but that isn't the point of the demand letter. Rather, you are mostly showing the court that you tried reasonably to solve your problems before going to court and gave the other guy every notice and opportunity to work with you beforehand. You were the reasonable person here, and now the court needs to help you deal with the unreasonable party, your opponent, who by now will look quite foolish.