You must have loads of miles to your name. You have often come across the miles staring back at you on the balance sheet, or treatments given to your car, or paying bills at the mortgage company. You come across it: the travel miles are melting down to one single point that can be traded. A fleeting thought lures you, and you impulsively hurry to tap the 'confirm' button; then, swiftly, a voice inside whispers, "Is this a good idea, or am I getting kicked out of the MileagePlus club forever?" It’s a fair question. To the airline, miles are like secret state secrets; they want to keep them under lock and key. To you, they’re a currency you earned while sitting in a cramped middle seat next to a toddler who thought your armrest was a drum kit. The truth is, there are risks when you choose to sell United miles but like any financial move, the "scary" parts usually come from a lack of information. Let’s break down the 7 things you need to consider to keep y...