A good 57 million Americans rely on Medicare to provide crucial health benefits. It's especially important for retirees, who are living on a fixed income and no longer have employer-provided health insurance. Here's how you can make the most of this critical program -- and look after your health in the process.

1. Keep your premium costs to a minimum

Though most Medicare enrollees don't pay a premium for Medicare Part A, which covers hospital visits, Parts B and D, which cover preventative care services and prescription drugs, respectively, do come at a cost. You can keep your premiums as low as possible, however, by signing up for Medicare on time.

Doctor with senior male patient


Your initial Medicare enrollment window kicks off three months before the month you turn 65 and ends three months after the month you turn 65. All told, you have a seven-month opportunity to sign up for coverage, but if you miss this window, you'll risk a number of penalties that could cost you a sizable chunk of money over time. Specifically, for every 12-month period you fail to enroll in Part B upon becoming eligible, you'll face a 10% increase in your monthly premiums.

It pays to sign up on time for Part D as well. If you go 63 days or more without Part D coverage, you'll face a late enrollment penalty equal to 1% of the national base beneficiary premium -- currently $35.63 -- times the number of months you fail to sign up for a plan. So if, for example, you sign up for Part D 22 months late, you'll pay $7.80 more per month. Pay attention to enrollment deadlines, as doing so could help you keep your costs down.

2. Keep track of the services you receive

While you'd hope you could trust all providers to do the right thing and put your healthcare needs above all else, unfortunately, it's not unheard of for a provider to game the system and attempt to bill you -- and Medicare -- for services that aren't valid. Medicare fraud is such a major issue that a specific task force was established 10 years ago to prevent it. In fact, in 2015, more than 200 medical professionals were charged with Medicare fraud.

To protect your rights -- and finances -- as a patient, keep a detailed record of the services you receive so you don't wind up getting billed, whether intentionally or not, for charges you shouldn't be liable for. Furthermore, if you have reason to suspect that a provider of yours is engaging in fraud, speak up. Eliminating shady medical professionals from your list of providers can help you get the best possible care while avoiding unnecessary costs.

3. Sign up for Medicare Advantage

There's a reason over 17 million Americans are now enrolled in a Medicare Advantage plan. Medicare Advantage, also known as Part C, offers a number of key benefits that traditional Medicare can't match.

Medicare Advantage plans are available through private insurers that are approved by Medicare. While the specifics of each plan differ, most offer services not covered by traditional Medicare, like vision and dental care. Furthermore, unlike traditional Medicare, Medicare Advantage plans come with a maximum out-of-pocket limit, so while you might spend some money on your plan's premium, you'll also lock in a spending cap for the year. It pays to read up on Medicare Advantage and see if it's right for you.

4. Get your free health screenings

Neglecting your health doesn't just compromise your long-term well-being; it also opens the door to more expensive treatment down the line, especially when minor medical issues escalate into full-blown problems. Unfortunately, a large number of Medicare beneficiaries aren't using the program's free -- yes, free -- preventive health services.

Take the "Welcome to Medicare" exam, for example. It was introduced back in 2005, offering a free initial wellness visit for new enrollees. Yet as of 2011, there were only 100,000 such completed exams on record per year, even though over 2 million seniors became eligible for Medicare annually.

Even if you missed the boat on your initial wellness exam, you can still benefit from the program's free preventive care services. Enrollees are entitled to a yearly wellness checkup, as well as other no-cost services like depression screenings and weight loss counseling. It pays to take full advantage of these and other free Medicare perks, because doing so could save you money and protect your health at the same time.

Making the most of Medicare often boils down to learning more about how the program works. The more you read up on Medicare, the better positioned you'll be to maximize your benefits in the long run.