encrypt your hard drive (full disk encryption, or FDE for short).
standard LVM encryption is the best option and should be available when installing your linux distro.
for a disk that is not part of your operating system, a portable drive for example, dmcrypt/LUKS is the best option but veracrypt is available on all platforms. keep in mind your installer may or may not encrypt your GRUB and there are several ways of dealing with that issue which are discussed in the Paranoid #! security guide linked in the introductory resources below. keep in mind disk encryption means nothing to an experienced attacker with physical access if you have not completely shut down your computer and wiped the RAM.
encrypt your emails.
PGP is pretty much all we have, but it is all we need.
https://www.enigmail.net/ your metadata may still be collected. if you care about metadata, use a disposable email account or a trusted provider. suggestions include protonmail or cock.li.
encrypt your instant messages.
for better or worse XMPP+OTR is still our best bet.
https://otr.cypherpunks.ca/ i would not depend on anything else. even if the crypto in other apps is theoretically sound, the implementation fails or the distribution method is inherently flawed. cryptocat is an unpopular, but good option. telegram, tox, and wickr are fucked. do not even bother. you might as well use skype.
use a local password manager (no cloud bullshit).
any. it is better than what you are doing now.
do not reuse passwords. seriously.
if you do, consider your password public knowledge.
bypassing a login wall? sure. fuck it. who cares if someone else uses it.
anything you care about? no. absolutely not.
modify some settings
enter about:config into your url bar and apply the following modifications. do not bitch about there being too many options. that is the fucking point. you cannot even configure many of these settings in other browsers without modifying its source or building addons.
https://pastebin.com/raw/T8TeepZP
the changes listed above are unambiguous and unopinionated. you can go a much further than this at the expense of comfort and convenience. consider modifying some of the settings listed on https://github.com/pyllyukko/user.js/blob/master/user.js depending on the sacrifices you are willing to make for privacy and security.
do not use chrome. chrome is a closed source browser by a for profit corporation. firefox is an open source browser by a non-profit organization. use your head.
do not use chromium either. it may be open source, but it still phones home.
