Not all shoes fit the same, so you won't necessarily wear the same size in every shoe style. Try on different sizes to get the best fit. Wear hosiery and take a pair of thick socks when shopping for shoes. That way, you can try on different shoes with the appropriate hosiery to make sure the shoes are not too loose or too tight. Try to shop for shoes in the afternoon.
Fluid retention can cause feet to be wider at the end of the day.
Make sure the widest part of the shoe lines up with the widest part of your foot. Otherwise, the shoe will pinch your foot. Wiggle your toes. The toe box should be wide enough to allow for a little wiggle room. Check the length.