You can check the 'do it yourself' section.
Further, make sure that you receive all the communications in writing, i.e. you get their settlement proposal in their letter head and also receive the account settled letter after final settlement signed in ink. Don't make any payment over the phone or authorize them to withdraw from your account, make payments only through moneygram or debit card.
I'm assuming that you are dealing with a collection agency. Hence make sure that you receive proper validation from them before making the settlement arrangement.