Depends on who you think is spying on you and who you want to reduce. Who is "they"?
The government is spying on you always and collecting everything you do. You can do little about that except encrypt your traffic until it gets outside your borders (then a foreign govt. will spy on you). The govt. is aided in spying by secret demands to companies like Google for the data they harvest. That is where you can effect greater change.
Instead of using Chrome which funnels everything you do back to Google use another browser. Then Google only harvests through your use of their services and their spying code, such as Google Analytics (GA), embedded into other websites. Reduce that some more by blocking GA in one way or another to prevent that spying: ad blocking, no javascript, take your pick. Reduce the amount of data you give to Google through use of their services: use another search engine; use another email service. Avoid Youtube where possible. Look for your favorite people elsewhere. Try the slightly unreliable Invidious front end.
Facebook is probably just as much a problem as Google. There is the website itself to avoid however you also need to avoid Facebook's "share" code put on other pages which still tracks you even if you don't have an account. They build a "shadow profile" for those without an account. They also own Instagram and Whatsapp so if you use them you are still using Facebook.
There are much more hidden companies that are probably spying on you. Cloudflare in an infamous example. They sit in the middle of many connections, even so-called secure ones (https), to provide DDOS protection and up-time reliability. This might be impossible to avoid as a user because you can't control how a website owner configures their systems. It sometimes looks as impossible to void as govt. surveillance.
Depends on who you think is spying on you and who you want to reduce. Who is "they"?
The government is spying on you always and collecting everything you do. You can do little about that except encrypt your traffic until it gets outside your borders (then a foreign govt. will spy on you). The govt. is aided in spying by secret demands to companies like Google for the data they harvest. That is where you can effect greater change.
Instead of using Chrome which funnels everything you do back to Google use another browser. Then Google only harvests through your use of their services and their spying code, such as Google Analytics (GA), embedded into other websites. Reduce that some more by blocking GA in one way or another to prevent that spying: ad blocking, no javascript, take your pick. Reduce the amount of data you give to Google through use of their services: use another search engine; use another email service. Avoid Youtube where possible. Look for your favorite people elsewhere. Try the slightly unreliable Invidious front end.
Facebook is probably just as much a problem as Google. There is the website itself to avoid however you also need to avoid Facebook's "share" code put on other pages which still tracks you even if you don't have an account. They build a "shadow profile" for those without an account. They also own Instagram and Whatsapp so if you use them you are still using Facebook.
There are much more hidden companies that are probably spying on you. Cloudflare in an infamous example. They sit in the middle of many connections, even so-called secure ones (https), to provide DDOS protection and up-time reliability. This might be impossible to avoid as a user because you can't control how a website owner configures their systems. It sometimes looks as impossible to void as govt. surveillance.