+1 to what kaiser said above. Any of the popular/top-rated backup plugins in the WP plugin repository will do the job of backing up for you. this one is one of the most popular ones... https://wordpress.org/plugins/updraftplus/ The hard part is restoring your back up files. Hopefully/realistically, restoring shouldn't need to happen often. For the relatively small number of times you need to restore, I think it's worth paying someone to do that work. It has never cost me more than $50.
-- Be aware, a database backup doesn't backup up your images! So keep a local copy of all your images.
-- DON'T rely on your host/anyone else to make backups for you, unless you pay them and you have a large website, then you can look at a dedicated service like VaultPress.
--If possible make your own backups and store them on a) your computer, b). a usb and c). online such as dropbox.
-- Delete any unused plugins, themes and images as they add a lot of space to your backup.