UpdraftPlus is an excellent backup option, and the free version works well. (The premium version has more options, and you can choose more locations to send the files.) A nightly backup for most sites is sufficient – set it up to run overnight when traffic is lower to make sure it does not slow down your site. If you want to be sure it’s a full backup and to have this available for “disaster recovery” (or if your host disappears!), make sure you’ve selected all files and your database, and be sure to have it saved on a remote/cloud server (not locally on the same server).