I am not going to tell you how to save it or invest it. But I will tell you how to spend the almighty dollar...at a vending machine. I learned this from several years working experience at an arcade. If the bill acceptor is not taking your bill and you have flattened it at least once - STOP - instead do the opposite, wrinkle the bill up. I can almost guarantee you that the acceptor will then take it without any issues at all. It may seem like it is against common sense but it works. And acceptors do not jam like they used to. The only thing that really need to be flat are the corners. Change machines / Vending don't like extremely flat bills because they can reflect too much light to the optical sensors...these machines are expecting used currency so they think your crisp bill is counterfeit. Whenever I see someone at the pop machine here at work having trouble, I grab the bill from them and crumple it before their eyes. They get mad until it works perfectly. So I just thought I would share this tip...crumple away!