A bunion is a shifting of the bones in your foot so that it looks as if you have a prominent bone on the inside of your foot. It is usually associated with the big toe shifting outward or towards the smaller toes so that again you have this angulation in your foot.
So the shoes that you choose if you wanna avoid getting a bunion is to avoid wearing pointy shoes and those with a narrow toe box. The narrow toe box and the pointy toe formation starts to push that large toe over creating and putting pressure on to that bunion.
After you take off your shoes it's very important to stretch the large toe and try and get it back into that alignment and out of that AB ducted or triangular position. A great stretch that you can do after taking off the shoes. Take an elastic strap. Place it on both of your large toes so it's looping the large toes and then you're gonna stretch your feet out which will place a pull on both of your large toes. This stretch is gonna stretch a small muscle that you have inside your foot that pulls the toe over. Hold the stretch for at least 30 seconds and repeat three times.
For women who already have a bunion and are experience pain in the bunion while wearing their high heels I recommend they see a podiatrist and often times surgery is recommended as a last resort to reposition the foot and get that toe back in alignment.