If there are three things millennials need to know about money, CNN’s chief business correspondent Christine Romans thinks rent costs are at the top of the list. “You’re probably paying too much rent,” she says. Aim to pay 30% of your annual earnings or less in rent; a lot of millennials pay almost 40%. Number two: Don’t think your student loans hold you back from investing. If you’re in a repayment plan, investing in your 401(k) can actually lower your monthly payment. Three: Save more money than you’re saving. Think about living on 85¢ of every dollar you earn.