Use a password manager and use different, complex passwords for every site. (The password manager will make it easy to generate and save new, secure passwords.) The one I use is OnePassword (paid plan).
Eventually, one of your accounts will probably be breached in a hack. It's a lot more of a problem if hackers find the same password for every account. If it's a one-off, it's much less dangerous. Also, complex passwords will be less subject to brute force hacking.
One of the most secure setups you can have is Firefox with strict mode tracking protection.
To enhance your privacy protections further, add these two extensions, both from the trusted Electronic Frontier Foundation:
For extra tracking protection you can also add Ublock Origin, a very good ad blocker.
(If you want to use Chrome instead, all the extensions above can also be used.)
And also add the browser extension for your chosen password manager so that passwords will be automatically filled in.
Try not to add any additional extensions, especially from unknown origins, as every new extension introduces a new potential vulnerability.
Firefox is privacy-focused and its user experience has gotten a lot better in recent years.
Regularly restart your phone and computer to allow updates to install.
The longer you have old code with known vulnerabilities running on your machine, the easier you are to hack.
Many services now provide two factor authentication, which will have you enter in a code sent to your mobile number or authenticator app after you sign in.
Two factor auth makes your accounts harder to hack. At least set it up for all your banking accounts and your email accounts.
You probably know how to do this already
Many apps track a lot of your data, the fewer apps on your phone the fewer apps tracking you (and your phone will probably work better too.)
If you did all these steps you are being proactive in protecting your data online!