I never really thought about this before. It's not like having perfect eye-sight makes you impervious to sketchy individuals. There are ways to tell what denomination cash is, like the size depending on the country or phone apps that look through the camera. I suppose you could OCR a restaurant bill to catch overcharges, but it's pretty silly for a restaurant to risk scamming a potential returning customer. I don't know what a sketchy environment I would want to be in would be.

So physical desfense and not being taken advantage of is pretty much the same for people with perfect sight, I've taken self defense classes and I know many of my visually impaired friends have as well. In the city where I live there are services that can give you that training for free. For specifics we're taught how to throw people that are grabbing us from behind and taught mostly to use our elbows to jab them in vital places we can feel.

Paying a bill at a restaurant is kinda tricky if you're paying with cash. (you have to trust someone to tell you how much your meal was) paying with card isn't really a problem since the card is taken elsewhere anyway. As for using cash there are devices and wallets that can tell you what type of bill it is so you know if you're being lied.

Be prepared for the worse, but hope for the best. Seldomly have I been taken advantage of, so I don't think about it. However there are identifiers for meveroy and other things. Be alert and defend yourself normally physically.