Use rolled up thick winter socks to stretch out your shoes. For even better results, roll up your socks, place in the freezer overnight and then squeeze them into your shoes to stretch them out. Leave the socks in the shoes until the socks have started to defrost.
Leather Stretch Spray
Leather stretch spray is excellent for leather shoes! With this, all you have to do is put on your shoes, shake the spray, spray it onto the area of the shoes that are too tight for you but do not rub in the foam, and then keep your shoes on for a few hours until the white foam has properly absorbed into the shoe. You can repeat this process several times to gradually stretch out the shoes. By wearing your shoes after applying the spray, your shoes will stretch out to the natural shape and size of your feet. The great thing with this option is that your shoes will stretch out neatly to mold the shape of your feet, i.e. to the shape/size you need them.
A Shoe Horn
Yes, a simple, old-fashioned shoe horn is a great tool for helping you put on your shoes more easily, or to help stretch out your shoes a little.
Take a sealable food bag, half fill it with water, seal it, place in the freezer and leave overnight. Take the sealable bag out of the freezer, by now it should have turned to ice. Place the bag of ice into the shoe and leave until the water has defrosted.
I hope that helps! I've tried all of these tricks many times and they've all worked for me. My advice to you would be to try each method and see which works best for certain shoe types. I find that sometimes some shoes respond best to the ice trick, whereas the sock method is better suited to other pairs.