You can start by looking at https://kagi.com/stats?stat=leaderboard and adjusting domains that make sense to you. E.g. I have all Pinterest lowered, as well as w3schools.com as I prefer developer.mozilla.org (which I raised instead).

For bangs I’m pretty sure the default ones might be enough – just use them! Some of my go-to bangs are !gh, !gm for Google Maps (Kagi Maps are sometimes not as good in Asia), !yt, !mdn, and !amo for addons.mozilla.org.

I also have this redirect rule:

  ^(https://www\.nytimes\.com.*$)|https://archive.ph/2025/$1

I just stumbled across cooked.wiki recently. It allows you to convert any bullshit online recipe to a no-frills ingredient list and instructions. I've only tested it a couple times and I know I'll rarely remember to use the shortcut (https://cooked.wiki/<recipe-url>). But setting it up as a redirect rule from search results might be the thing that pushes usability over the top.