If possible, stick to the 3-2-1-1-0 rule. Keep 3 copies of your data on 2 different types of media. One of the copies should be kept outside your home. You should also have an offline copy. Zero errors should occur when restoring the data.
Many apps have their own backup or export functions that you can use. You should also think about important apps such as 2-factor apps or password managers when making your backup. The settings can usually be easily exported from these.
If possible, use open-source backup software such as "Neo Backup". However, this often requires superuser rights (root). However, a simple regular copy of your most important data on a USB stick is also a good start.