I want to browse websites anonymously.
Use the anonymous Tor web browser — it’s free and available for Linux, Mac, Windows, Android and iOS.
I want to stop my ISP (or Work or School) from monitoring me.
I want to buy something anonymously with a credit card.
I want to visit blocked/censored websites.
You can use a VPN (virtual private network).
I want to keep hackers away while I travel and use WiFi hotspots.
I want to email privately.
You a reasonably private email provider (e.g. Namecheap) or Countermail. The free GnuPG can be used with any email account, but it takes some time setting up. The easiest tool to use is Mozilla’s email program, Thunderbird with the Enigmail extension.