Three street-style fixes that keep your proportions sharp: a jacket knot, gel heel grips, and a nail file for snaggy knits.
The bag-handle knot that turns any jacket into a crop

There are outfits that look fine in your bedroom mirror and then immediately go soft the second you step outside. For me it's always the too-long outer layer: a bomber that's not quite a bomber, a trench that eats your legs, a denim jacket that hits right at the widest part of your hip. Street-style photos make it look like everyone owns the perfect cropped version of everything. I don't. I cheat, and it takes about ten seconds.
Put your bag on your shoulder first. This matters because the bag strap is the "third hand" in the whole trick. I do it most with a medium crossbody (Coach Cassie size) or a shoulder bag with a sturdier strap (think a Longchamp Le Pliage with stuff in it, not an airy chain that slides). Grab the front hem of your jacket with your free hand, right where you want the new "crop" to land. Fold that hem under once, then once more, so the raw edge is tucked and the fold looks like a deliberate band, not a panic roll.
Now the move: pull that folded bundle up and over the bag strap that runs across your chest or shoulder. Tie it once like you're starting a shoelace knot, but don't cinch it to death. You want tension, not puckering. The strap pins the fold in place and keeps the knot from traveling north while you walk. If your jacket has a slippery lining, give the fold a little pinch so fabric grips fabric before you knot. Then do a quick mirror check from the side: if the back is still long, reach behind and do the same fold-and-tuck under the strap where it sits on your shoulder blade. It sounds fiddly, but after you do it twice you can fix it while waiting for the crosswalk light.
This is my go-to for the "big jeans, small top" silhouette when I only brought one jacket. It also saves the look when you're wearing wide-leg trousers and chunky sneakers and suddenly the whole bottom half reads like a moving blanket. The knot gives you waist back, the proportions snap into place, and you still get to keep the jacket on when the wind comes off the subway stairs.
Gel heel grips for sneakers that eat your socks

If you've ever bought a pair of Sambas, Gazelles, 550s, or any of those clean, low-profile sneakers that look perfect with baggy jeans, you know the dark side: the heel counter is a tiny guillotine. You think you're fine, then ten minutes into the day your sock is sliding under your arch and you're doing that subtle street-style hobble like nothing's wrong. I've tried the obvious stuff. Thick socks change the whole vibe. Moleskin peels when your foot sweats. Bandages roll up and become their own problem.
The thing that finally stuck for me is gel heel grips, the kind meant for dress shoes. Dr. Scholl's makes a solid pair, and so do the generic versions at CVS and Target. They look like nothing, but they do two jobs at once: they add just enough padding that the heel edge isn't a blade, and they take up a hair of space so your foot isn't lifting and slamming back down every step.
Here's how I place them so they don't feel like a lump. Clean the inside heel of the shoe first. If you skip this, the adhesive is fighting factory dust and whatever lint has been living in there. I use a little rubbing alcohol on a tissue, then let it dry for a minute. Peel the backing off the gel grip and set it slightly higher than you think, so the bottom edge doesn't sit right where your heel bone presses hardest. Press it in from the center out with your thumb, hard, like you're applying a screen protector. If you get a wrinkle, pull it off and reset it before you walk. Once you take steps on a wrinkled grip, it stays wrinkled.
On days when I'm doing real mileage (museum, errands, and then an outdoor dinner because I didn't plan my life), I double up the prevention: gel grip in the shoe and a tiny smear of Body Glide on the back of my heel. Not deodorant. Not Vaseline. Body Glide. It's what runners use, and it doesn't stain your socks the same way.
The street-style payoff is boring but huge: you can keep the exact sock height you intended, keep the sneaker unlaced the way you styled it, and you won't spend the day thinking about your feet. Also, the grips make older sneakers feel "new" again in the heel, which is convenient when the upper still looks great but the inside has turned into sandpaper.
How I stop a sweater snag from turning into a ladder

My street-style uniform has a lot of knitwear because it photographs well and forgives a rushed morning: a slightly boxy merino crewneck, a ribbed polo knit, a cardigan I can toss over a tank. The problem is that city life is basically a snag obstacle course. You catch on a tote zipper. A ring scrapes a sleeve. Your bag hardware bites the hem when you swing it around on the train. If you pull the snag like it's a loose thread on a cheap T-shirt, you're going to turn one tiny loop into a visible ladder. Ask me how I know.
I keep two things in my bag for this, and neither is fussy: a mini nail file (the thin emery-board kind) and a tiny folding snipping tool like the Conair compact scissor or nail clipper. The nail file is the sneaky hero. When a snag happens, the first move isn't cutting, it's calming down the area so the snag stops catching again and again while you're walking.
Step one: don't yank. Pinch the fabric around the snag and give it a few gentle tugs in different directions, like you're trying to coax the loop back into the knit. If it's a sweater with any stretch, that alone often makes the loop shrink. If the loop is still there, flip the garment inside out as best you can (bathroom stall, car mirror, whatever). Use the nail file to lightly "comb" the loop back through from the inside. You're not sanding your sweater. You're using the file's texture to grab the loop and encourage it to sit on the inside where it belongs. This works absurdly well on finer merino and jersey knits. Chunky knit can take more patience, but it still helps.
Only after the loop is on the inside do I cut anything, and I only cut if there's a long tail that will keep snagging. I use the smallest snip possible, right at the tail, and I leave a whisper of length so I don't pop the stitch. Then I rub the spot between my fingers to fuzz it slightly, which sounds wrong but makes the repair visually disappear. If I'm wearing a dark knit, I press the area with my thumb for a few seconds to warm it and help it settle.
The street-style part of this is that you can keep wearing your "nice" knits outside, with bag straps and jewelry and all the stuff that makes an outfit look finished. You're not treating your sweater like a fragile museum object. You're just refusing to let one dumb snag become the only thing you see in every photo for the rest of the night.