Walk without holding it on
Stand in both sandals with your weight distributed normally. Your foot should sit on the sole, not extend beyond its edges. Then walk at your usual pace. Notice whether you curl your toes to stop a slide falling away or shorten your stride because a strap shifts. Those adjustments can be easy to miss during a few careful steps towards a mirror.
A back strap changes how a sandal stays with your foot. So does the position of the strap across the front. Neither a very open design nor a heavily strapped one is automatically better; they simply hold different parts of the foot. Try fastening adjustments before deciding, and make sure there is room to adjust in both directions.
Check the places that touch
Run a finger along the inside edges and seams before putting the sandal on. Once it is fastened, pay attention to buckles, toe posts and the outer edge near the little toe. A decorative knot can be attractive in a photograph but uncomfortable where it presses. Do not overlook an immediate rubbing point because the rest of the shoe feels airy.
Test on the surfaces the shop permits. A soft fitting-room carpet tells you less about a sole than a firmer floor. Consider where you will actually wear the pair: a short dinner outing, errands or a holiday with long walks are different uses. A flat heel alone does not establish comfort or suitability for all of them.
Fit it into the day
Try the sandal with the trouser or skirt length you expect to wear. Fine straps can look visually slight beneath a large hem, while broad straps make a stronger horizontal line. Use that difference deliberately rather than treating either as universally flattering.
Before buying, open and close the fastening yourself. An awkward buckle can become a daily nuisance. Check the return policy before any longer try-on at home, keeping the soles clean. If your plan depends on the sandal becoming an entirely different shape after a week, give another pair a chance. A summer shoe still needs to work when you leave the chair.
