Getting the right pair of running shoes can make the difference between comfortable, pain-free running or limping around the next day bruised, bloodied and wounded. But how can you tell if the nice looking pairs you try on in the store or that pop up in your browser are going to be a good fit for you after 5 to 10 miles, or after weeks of running a lot of miles? These five keys can make it more likely.

1. Get the right size.

Everyone knows their shoe size, right? Don’t be so sure. Geoff Gray, a physical therapist and researcher, has tested hundreds of runners at his Heeluxe footwear research lab in Santa Barbara, California. He estimates that 75 percent or more come in with shoes that don’t fit. “Most people are wearing a shoe that is a half size to a full size too small,” Gray says. This is a problem, because a shoe that crimps your foot not only sets you up for blisters and hot spots, but can also damage your toes and alter your stride. “I would rather have people wear a shoe that is half size too large than half size too small,” he says.

Better yet, get them the right size by having them measured and fit at a specialty running store. A good store will measure your feet, or, at minimum, bring out a range of sizes for you to try. Either way, by trying on multiple models, they will help you find the size that fits right for running. That number that will usually be a full size bigger than your street shoes, says Philip Snyder, manager of the Berkeley Park Running Company in Denver, not to mention slightly different for every brand and model. Go in with an open mind.

2. Get the right shape.

Just getting the right numerical size isn’t enough, however. Shoes are built on the specific length and volume of a last—a foot model that determines the size and shape of every shoe. Every company’s lasts are slightly different, plus, most brands have different lasts for different models or lines within their offerings. Feet, too, are all different: the height of the arch, the height and volume of the instep, the width of the heel—all can differ significantly from foot to foot, even between feet that are the same size. Spencer White, vice president of Saucony’s Human Performance & Innovation Lab, points out that within the normal population even the location of the metatarsal heads, the widest part of the foot and where it bends, can vary by up to 10mm forward or back.

Getting the right fit requires matchmaking. “So much, it is fitting the shape of the foot to the shape of the shoe,” says Brian Morrison, Operating Partner of Fleet Feet Seattle. New technology can help, like Fleet Feet’s fit id program, which scans and produces 3D information about the foot’s size, shape and volume. SuperFeet’s FitStation goes one step farther and gives a list of possible matches based on their extensive database of shoe shapes. With or without technology, nothing beats putting a shoe on your foot.

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After lacing up a shoe and snugging each eyelet, Kris Hartner, founder of the Naperville Running Company stores in suburban Chicago, says his shoe-fitters check to make sure the the heel doesn’t slip, a good indication of whether the last fits your foot. “From there,” Hartner says, “We don’t want you to notice the shoe that much.” They will compare models side by side, two different styles at the same time on the right and left feet, having the customer walk around in them, looking for the ones that “disappear” and feel light on their feet. Customers try an average of six to eight models, Hartner says, eliminating options until they have one pair that they’ll run in on the treadmill to ensure they fit at speed.

3. Get the right support.

That treadmill run is also a chance to see how well the shoe complements your stride underfoot. Gone are the days when shoe fitters watched you on a treadmill, diagnosed your pronation level (the inward rolling of your foot and ankle) and fit you neatly into a category like “neutral,” “stability” and “motion control.” Science and experience has shown that the control features that defined those categories didn’t work as well as advertised, and, moreover, pronation isn’t a problem that needs to be controlled for most runners. (Every runner pronates to some extent, and overpronation is better controlled by doing drills to gain strength and improve form.)

That said, while motion control has been mostly debunked, stability is still important. Different runners need and prefer different levels of stability, a term which combines width, geometry, sole stiffness, upper design and more. Brands are attacking the need for stability in novel ways: guide rails, varus wedges, late-stage rockers, stability pods, reinforced upper zones, as well as multi-density midsoles, which work for some runners, perhaps, experts suggest, mostly because of the durability they provide in key locations.

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How do you know what support is right for you? Brands are still working to quantify this, the latest method being the Super Feet/Brooks FitStation, which not only measures foot size and shape but also uses pressure-plate data to assess the motion of your knee and ankle. “We’re getting a modernized gait analysis that looks more holistically at the body,” says Carson Caprara, Director of Global Footwear Product Line Management at Brooks. Soon, Brooks will use this data to inject hardness into zones of the sole to create customized shoes which will “work better with what the foot is trying to do already,” Caprara says.

Right now, the data from the FitStation or the expertise of a shoe fitter can help you determine what level of support you may need and narrow the range of shoes to try, but, in the end, your own perception is still the best way to judge what works. The right shoe will land where you expect it to and bend where it is supposed to; it will let your foot move as it wants, while providing invisible support, keeping you from drifting out of your comfortable, preferred pattern because of weakness or fatigue, and all without altering your stride.

4. Get the right ride.

While shoes have always produced different sensations due to their midsole foam, thickness, firmness and shape, the variety of materials and designs is now greater than ever and brands are creating categories for different rides. Brooks shoes fall into four silos: Cushioned, Energize, Connect and Speed. Nike recently reorganized its lines into similar categories: Air, React, Free and Zoom. Other brands may not use these terms, but they have shoes that correlate to each underfoot experience. A shoe’s ride answers the question, “What do you like to feel underfoot?” A soft, cushy pillow? Cushion with rebound? Hardly anything between you and the ground? Or a firm, fast turnover?

While these shoe silos can help narrow your search, your experience might not correlate with how the shoe is marketed, as each component interacts uniquely with your specific weight, pace and motion patterns. “As much as the brands are trying to capture [an experience], everybody still feels things differently,” Morrison says. “What you realize, in actuality, some people feel will feel completely the opposite.” Be aware of the different ways shoes can moderate your interaction with the ground, pay attention to the different types of “comfort” in a shoe and experiment with a wide variety of models to find the one that speeds you along in your preferred style.

5. Trust Yourself

The best shoe for you is going to be the one that feels best while you’re running. This makes sense intuitively and research has proven it to be true. But we often ignore it, preferring to trust marketing, or our running buddy, what has worked in the past, or a well-meaning salesperson. A good salesperson will help you find your best shoe, not prescribe one for you. There is no substitute for testing shoes as you will use them: on the run, at multiple speeds. Pay attention to every detail of size, shape, support and ride. The shoes that feel like an extension of your body, are the ones you should take home.