Stabilizing Sewn Shoes

Dear users, dear authors,
How do you reinforce sewn shoes—specifically the sides of sewn shoes, not just the sole? Or is it not necessary to reinforce the sides?

For some styles, it might not be necessary to reinforce the sides at all. For many ballerina-style shoes, I assume that interfacing is ironed in for reinforcement.

It comes in various weights and thicknesses and is also used in bags and clothing. More details will be provided in the ebook.

Best regards,
Sonja

With espadrilles, it’s absolutely necessary, unless you’re using very sturdy fabric. But with canvas, for example, they tend to “sag” quite a bit—even if you add an elastic band at the top, it doesn’t help; the heel really needs to be quite stiff.

Thanks for your advice.
What kind of sole is best if you actually want to go outside in these sewn shoes?