How do you back up your photos?

I’m a hobby photographer and software engineer working on an open-source backup app. It works for all kinds of files, but I’d like to make it especially useful for photographers.

I’d love to understand how people actually handle this:

How do you store your photos after a shoot?
Do you have a real backup, or more of a “good enough for now” setup?
What makes backing up photos annoying, confusing, expensive, or easy to ignore?

Thanks!