A good pair of trainers for work has a bit of weight to the sole without feeling clumpy, and the upper gives slightly when you press it rather than snapping back stiff. You want to be able to bend it a little in both hands and feel it flex somewhere in the middle, not just at the toe. If it feels like a running shoe pretending to be smart, or a leather shoe that's had its heel sliced off, put it back.
If you've got nothing suitable yet, start with a plain leather or leather look trainer in white or a muted colour rather than anything chunky or branded down the side. It sits under trousers and under a skirt without arguing with either, and it reads as deliberate rather than like you gave up halfway through getting dressed. Save the more sculpted, sporty shapes for once you've got the quieter pair and know how far you're willing to push it.
Fit is where most people come unstuck, because trainers are sized differently to the shoes they're replacing in your work rotation. Go up half a size from your usual trainer if you're wearing thicker socks or tights underneath, and always try them with the socks you'd actually wear, not barefoot in the shop. Watch the heel especially, it should hold your foot without you needing to grip with your toes to stop it slipping, and if there's a gap at the back after a short walk round the shop, that gap becomes a blister by eleven o'clock. A toe box that's too narrow is the other quiet failure, fine standing still, agony after six hours at a desk and a walk to the station.
Worn regularly, the upper softens properly within a few weeks, creasing where your foot actually bends rather than cracking in odd places, and the white ones will pick up a grey tideline round the sole whatever you do. A damp cloth after a wet commute, stuffed with paper rather than left to dry near a radiator, keeps the shape honest for longer. Rotate two pairs if you can manage it, because giving the cushioning a day to recover between wears is the difference between trainers that last a year and ones that go flat and sad by March.
The best ones have a sole with just enough spring that you only notice it on the day you forget to wear them and do the same walk in heels instead.
