Though working Americans have several options when it comes to saving for retirement, 401(k) plans are one of the most universally appealing. Not only do they come with generous annual contribution limits — $18,000 a year for savers under 50 and $24,000 a year for those 50 and older — but because they’re managed by employers, it’s easy to sign up and contribute. If you’re among the lucky 59% of workers who have a 401(k), here are some strategies that can really pay off in the long run.