Between planning goodbye drinks with your work wives, cleaning out your cube, and getting prepared for your next career adventure, odds are the last thing on your mind as you left your last job was, What the heck do I do with my 401(k)?First up, congrats on having a 401(k). Saving early for retirement is one of the smartest money decisions you can make, so you’re already on the right track. (If you start socking away money at 25, by age 65, you’ll stand to save nearly double what you would if you started saving the same amount ten years later.) That's why it's key not to lose sight of this hard-earned money when you switch jobs.How to handle these funds depends a lot on your situation, says certified financial planner Lazetta Rainey Braxton, founder of Financial Fountains . In fact, leaving your money right where it is may make sense, especially if your previous employer has better investment options at a more reasonable cost than your new company. That said, if you are ready to take the money with you (after comparing fees and investment options), Rainey Braxton recommends considering a direct rollover to a traditional IRA. This will help you avoid being taxed on your savings. Once you choose a financial institution, your broker can walk you through the entire process over the phone.