Write a formal legal letter by typing a concise, goal-oriented letter that makes your requests explicit and concludes with a promise of further legal remedies if necessary. Keep copies of any such letters you send, and mail them by certified mail with a return receipt requested. This allows you to challenge any later claims that the recipient did not receive what you sent them.
The letter should contain a concise list of relevant points. For example, a formal demand letter sent to your opponent should contain a brief list of everything currently in dispute. This is not only for the benefit of your opponent who may or may not already know all of this. If necessary, it serves to help your case with a judge if the matter goes to court.
Even though the letter may be going to your legal opponent, write the letter in a very polite and formal way. Writing insulting or impolite messages not only makes you look bad to others who may later read the letter, it makes your opponent less likely to settle the disputes in question in an amicable manner.
Make all demands specific in the letter. For instance, if you desire a specific sum from your opponent, request that exact sum. Use the letter to show how you calculated the exact figure owed, and demand payment by a specific due date.
Conclude the letter with a promise to pursue further legal remedies if your demands are not met.