Avoid commercial sites by adding your own flavor of top level domain (TLD) limitations, e.g. "(site:.org OR site:.net OR site:*.edu))"

For example: instead of returning the top result on ahrefs.com, this query:

• 'search operators "site" (site:.org OR site:.net OR site:*.edu))' makes it easier to find: "https://guides.lib.berkeley.edu/GoogleTips" in what would be a sea of SEO gamed results on .com domains.

Reference:

• https://guides.lib.berkeley.edu/GoogleTips