Regularly make a backup of your site in case it hacks or doesn't work properly due to some changes in a theme.
You have seen many big sites that got hacked and had no backup so they had to work hard to get the data.
Also I have seen many newbies who try new plugins that make changes to then theme, then the theme doesn't work.
But how you should make a backup?
You can use ALL IN ONE MIGRATION PLUGIN or BACKUP BUDDY that makes backup of everything for free. It has a paid version too.
If you don't wanna use the plugin, then here are what to backup.:
- Plugins
- Themes
- Databases
- Upload (images etc)
If you go to wp-content folder in file manager of your hosting, you will find three of these sub-folders: plugins, themes, upload.
It means you can make backup of it via FTP (Filezilla) manually too. For database, you can do manually or can use plugin.
I would suggest minimum create backup once a week.