I'm going to keep it short and to the point...
-Never email yourself your private key, backup phrases or passwords.
-Never keep private keys and backup phrases in a file on your computer.
-Keep private keys, backup phrases and passwords on a usb (or written on paper) which is not connected to the internet.
-Always use a different password on every website and exchange you use.
-Never keep crypto on any exchange.
-Always bookmark exchanges you use and sites like myetherwallet and only go there from your bookmark.
-Never give out your password and never give out your private key.
-Don't keep any crypto on a cell phone unless you plan to spend it soon.
-Don't use public wifi.
If anybody has anything constructive to add comment below.