Depending on the accident, you may find an accident settlement agreement available online from your attorney, insurance agent, insurance company or from one of several U.S. bar associations. If you must draw one up, be sure it includes all particulars of the accident, damages that will be covered and paid in full and those that will not. Once you have completed the agreement, ask your attorney to look it over to see if there is anything that has been missed. When you have an agreement from all of the parties involved, have it notarized and filed with the court. This will protect you just in case someone decides that he or she does not like the results and wishes to reopen it.
For more info, see How to Get a Collision Estimate Online