How do you stretch shoes without damaging them?

When I get new shoes I stretch them out and break them in with 1) THICK socks and 2) heat. I have these thick wool socks that I wear to both stretch them out and prevent them from causing blisters (not exactly a picnic to wear wool socks in the summertime but fall/winter it's nice). If you don't have thick socks you can just double or triple up your regular socks. I will also take a hair dryer and blow it at the shoes for about a minute to heat them up and make them looser/bigger.

Shoe repair shops have a specially formulated shoe stretch solution that's safe for leather and doesn't discolor it. While the solution is wet, they put a wood shoe stretcher in the shoe and turn it and then crank it up till you know stretch it to the correct width. As that solution dries, the leather will stay in the new stretched position.

Just to add to this, I would highly advise against soaking your shoes in anything. If your shoes are actually leather, water and moisture are going to destroy the material. If they’re synthetic, they’re probably water-resistant but not waterproof. In other words, you can wear them in the rain but if you soak the shoes they’re going to warp or become waterlogged.

I've gotten shoes that were just sliiiiightly too small before, and I tried the freezer trick. What is the freezer trick, you ask?? Sounds insane but fill a gallon baggie with water, close it TIGHTLY (make sure it's closed so it doesn't leak!!!!), then stuff it in your shoe. (This is more of a trick for sneakers than high-quality leather shoes, btw!) Put the shoes in the freezer overnight, and the baggies will swell because water expands when it freezes. They'll stretch out the shoes a bit. The next morning, remove the baggies and the shoes should be big enoguh to fit your feet comfortably.

The more you wear them, the more your feet will swell and the shoes will stretch. Just wear the shoes all day, preferably at home so you can change out of them if they start giving you blisters.

Wear thick socks, heat the tight spots with a hairdryer, and flex your feet. Cool while wearing. Use overnight for width/length adjustment. Apply before using stretchers or wearing. Place water-filled bags in shoes and freeze to expand.