Hi.
You have an interesting-looking collection there. There's no real golden rule for what to look out for. Stamps are so varied and variable, anything may or may not be collectable, depending what it is. The vast majority of stamps are of little worth however.
I'd be keen to sort through that box if I had it in front of me. Monetary worth is unknowable as we can't see them. If you can pull out some of the unusual ones or ones which you're curious about for whatever reason, try posting some better images, like for example, in this thread:
https://goscf.com/t/63418As mentioned, all the US ones with the horizontal lines and town names printed over the top are called pre-cancels. I don't know much about them, but I understand there are so many different ones in existence it is impossible to collect them all. A few might be worth something but I would guess yours are common, not valuable, as they have apparently been through the hands of collectors and dealers already, and left behind. Nevertheless, interesting to sort through and see what's there.
I see some British Commonwealth as well - Newfoundland, a block of four New Zealand. Commonwealth is very collectable. If you are interested in them, beyond what they are worth, maybe you could invest in a stock book (and tweezers/tongs) and get some of them laid out for better viewing?