Money & SavingsThis is a guest post by Lynnette Khalfani-Cox, host of the AARP Pay Down Your Debt Challenge, which is taking place on AARP.org through Jan. 29. Learn how to get started paying down your debt, join the Pay Down Your Debt group, and you could have a chance to win a prize. Lynnette will have a Twitter chat on @AARPMoney. Tuesday, Jan. 10, 3-4 pm EST. Ask her questions about credit and debt issues and follow via #debtchat. By Lynnette …