1. in System Preferences, open SPOTLIGHT
2. Uncheck -- FONTS, MUSIC, CONTACTS, CALCULATOR
3. add folders that u don't want searched.

That helped a lot!

It is still showing a LOT that I don't want to see. It wasn't always like this, and I don't remember changing any settings, but it is really almost worthless to use with everything it's showing. Argh.

Is it just returning too much for you or results that don't match the search? If too much, it could be the "results" tab (in spotlight preferences) is including more than you want.

A decent article on how to use Spotlight (the search engine that Finder uses): https://www.macworld.com/article/2919029/how-to-use-spotlight-in-yosemite-to-search-for-files-apps-web-info-and-more.html

You can use "cmd-f" in any finder window to bring up a more advanced search interface. E.g. you can use it to find just files that contain the string you're looking for, or files that are really big. And it's easy to limit the search to a specific folder or search the entire Mac.

If you think the results are not what you've asked for, you might (might) need to rebuild the Spotlight database. It's just two steps, this article shows how: https://support.apple.com/en-us/HT201716