Well this question is far too broad to possibly be answered in a single answer.
But here are things i recommend you do
-Use multiple emails. Have one email for your important things (like your bank) and then have other ones for signing up to websites or giving out to strangers. You can also use temp emails services and email forwarding services as well (id actually recommend that course of action personally).
-Try to never use the same password on multiple websites (or atleast any that can give identifiable information about you. if you sign up for multiple internet forums and dont have any personal info in those accounts, you could use the same password for both). But using the same password for multiple sites greatly increases the risk of your accounts being compromised. especially if those passwords unlock things like email in which they can use to gain access to every account you have linked with that email.
-Use adblocking software. Even though by using ad blocking software you are cutting the profits or even the lifelines of websites. ads are what keep the internet running and free. without ads there is no internet basically. BUT there are so many sites which serve malicious ads (even perfectly legit sites). and adblocking software will greatly reduce the risk of getting malware, hacked or scammed.
Personally i recommend "ublock origin". sites you know and trust dont have annoying or malicious ads and you want to support, go into settings and whitelist that website so it will serve ads.
-ALWAYS download software from the official source. never use 3rd party downloaders like cnet and softpedia and other places which host software/files. by downloading software from the official source, you are pretty much guaranteed that unless the software itself is malicious, that you wont get any malware/viruses from it. As sites which reupload software have uploaded modified versions which can contain malware/viruses.
And on a side note when installing software, ALWAYS read before clicking next. often time you can click agree to install spyware or malware. the software you download/install may be completely legit, but they "bundle recommended software" and are paid to do so. And this bundles software may be malicious. Opencandy is adware (they inject ads into your computer basically) is bundles with a lot of legit software.
So make sure to always choose custom/advanced install, and read everything and uncheck anything that may be additional software you dont want.
-Use decent security software. many free versions of anti-viruses are actually not good. they are pretty invasive. many of them are down right scareware/scams (they lie about viruses on their pc so you keep their av and buy the premium version *cough AVG cough*) or they are spyware (sell your information. *cough AVG and avast cough). and many of them bundle a lot of crap like toolbars (again avast and avg).
Most antiviruses are crap and not needed. something like malwarebytes is more then enough. it has better detection rates and no bullshit. The free version is fine (but free version has no real time monitoring). the pro version will scan things in real time. which honestly the pro version is worth the cost. its pretty cheap.
Lots of people have said eset nod32 is overall the best of the paid AV applications out there.
You can also use a software firewall to help with realtime protection. like comodo or zonealarm or my recommendation of windows 10 firewall control or privatefirewall.
Theres also the option of using sandbox software to run your web browser and any application you dont trust 100% inside a virtual environment seperate from the rest of your computer. Personally i recommend sandboxie. the free version is good. the pro version just lets you run multi sandboxes at the same time and no nag screen.
I personally use: windows built in firewall (not that user-friendly but works well) + malwarebytes pro + sandboxie pro. and thats it. never had 1 issue doing all of what i mentioned with minimal security software.
*Id recommend also changing your dns provider to opendns or google dns (can google how to do that). your isp's default dns is likely less trustworthy then either of those dns providers.
-Lastly. do your research. do a quick google search for what you are installing or what product/service you are using or wanting to use. you can pretty easily find out if something is a scam or fake by doing a google search about it.
use key words such as "review" or "scam" or "real"/"fake" and see what results come up. if you see a lot of posts talking about how bad the thing is you are looking at, id either steer clear, or proceed with extreme caution.
WOT (web of trust) is a decent addon to give a little extra input on websites. its user-generated ratings asnd reviews (yes there are bots, so just because a website isnt rated as good/safe does not guarantee it is). But looking at comments in WOT on the site can reveal a lot.
Then its just about being smart and thinking about things logically. (aka common sense). example such as beezid appeared on TV promoting auctions for the new iphone for $0.97... this is very obviously a scam/fake (which any penny auctions are. the auction never ends until the price is close to retail. the timer restarts when it hits 0 and other shady tactics). just because its on tv or it exists w/o the fbi or someone shutting them down does NOT mean its real/legit.
"if it sounds too good to be true it probably is", always proceed with caution and do research. it will save you time and money.