I've recently started using a self hosted SearXNG instance but I'm still using the search engines enabled by default (google, duckduckgo and qwant). What search engines do you have enabled or which ones do you feel you've gotten the best results with?
DDG doesn't like to exclude words from your searches though. It lets you exclude sites using the -site: parameter, but won't exclude individual words. And it constantly gives me search results that don't include the words that I'm searching for.
Have you tried using exclusive terms with quotation marks? Like "how to get rich fast" That should only feature sites with exactly that search term. Additionally you could link words with + between them i think.
I have tried, and it really doesn't work that well. Often I'm looking for a specific word, and if I search the page that DDG gave me, the word doesn't appear at all. Either it finds words it thinks are close enough, or it just ignores the request.