The malware and cryptoware threat is absolutely there. The first thing you should do is regularly make a backup of your files.
Besides that I recommend Malwarebytes or Heimdal Security Pro software together with your antivirus program. Those two will actively ... uhh, how do you say it in English? Scan or real-time check your status.
When you are the unlucky one who’s Dropbox is encrypted by Cryptoware.. Dropbox can put back a backup until 30 days I believe. Don’t wait to long contacting them.

For password use a password safe like Enpass or 1password. Copy paste your password is safer than type it out. You can also use a virtual keyboard for that or for your credit card codes. A keylogger will see only the ‘clicks’ then ☺︎