Change your browser.
Google is tracking your every move and then, to make matters worse, selling on that information to the highest bidder. There is a new browser built by the guys that built firefox that claims to stop all this. It blocks spam adverts and even gives you the option to earn cryptocurrency by looking at adverts. You can choose the frequency of these and even turn them off and on as you see fit. It only uses trackers to create an advertising profile for you and these details are not shared with anyone so no more third party trackers.
Install a VPN
what is it? a virtual private network. Basically it allows you to create a secure connection to the internet and shields your browsing activity from outside sources. It will also allow you to access restricted content in your country such a torrent sites/ cable channels etc not normally available to you.
Invest in decent anti virus.
I would suggest something like Bitdefender which has won countless awards for it's ability to identify and restrict all sorts of internet nasties. Make sure you run a full virus check on your computer on a regular basis to make sure you have no malware, Trojans or any other malicious software that can track and export your information to others.
Don't sign up for all sorts of stuff on the internet
People have a tendency to sign up for shops, websites, blogs, social media etc without giving any real thought to who is checking this information or whether it is being sold on to interested parties. restrict your online shopping to a few reliable sources and make sure to check or uncheck the boxes that allow them to sell your data if this is a legal requirement in your country as it is now in many.
Don't post private information on social media.
The reality is that when you punch in to your social media that you have been at said location that someone else somewhere is receiving that information and further adding it to build a profile of you as a consumer. Never post photos of yourself whilst you are on holiday. It might not do much for big tech companies but it pens you to being burgled, you don't want unsavoury characters knowing you are away from your home for an extended period of time. If you must post these then do so upon your return.