If a sharply lower 401(k) balance has made saving for your kids’ college education the furthest thing from your mind, automatic college savings plans could be key.

Like racking up airline miles for every purchase, a credit card linked to a college savings account, or 529 plan, can help you earn and automatically invest money—and let it grow tax free—until you’re ready use it for a qualifying higher educational expense.

Here’s how to start:

1. Pick a plan. There are a number of 529 plans to choose from, including direct plans and those sold by investment advisors.  As with a mutual fund, you can decide to invest aggressively when your kids are young, and less aggressively over time, or choose a target date fund where allocations will be automatically adjusted over time. 

Hot tip: Use online calculators to get your bearings. To fine-tune your overall savings plan, check out our college savings calculator at BankingMyWay.com.

To compare plan fees, expenses, taxes and other criteria, try this comparison tool at SavingForCollege.com.

2. Pick a card. To choose the college savings credit card that’s right for you, take a look at your everyday spending habits including how much you spend on groceries, dining out and online shopping.  Keep in mind that certain cards require you to set up a 529 plan and choose from funds offered by a specific investment advisor.

Here are some examples:

• For average shoppers: With a Fidelity Investments 529 College Rewards American Express Card (Stock Quote: AXP), you can earn 2% back on purchases to invest in a Fidelity 529 account. Each time you make $2,500 in purchases, you earn a $50 deposit for your designated Fidelity 529 account. There’s no annual fee and no limit to the rewards you can earn, but you’ll have to open a Fidelity-run 529 Plan to earn cash for college with this card.