Backup plans are a dime a dozen. Maybe less. What’s important is to have a backup plan for your Mac that works, covers any contingency, and does not require much maintenance. Here’s what I do in three basic steps.
First, you’ll need to invest in a couple of external USB disk drives. Why? The idea is to backup critical files, all files, and make it easy to get your Mac up and running if or when there’s a catastrophic failure.
Second, setup OS X’s Time Machine to copy files from your Mac to one of the external USB storage units. Use either SuperDuper! or Carbon Copy Cloner to copy files from your Mac to the other external USB storage unit.
Both apps will make a complete and thorough clone of your Mac’s internal disk drive or SSD, and by putting the clone on an external disk drive, should the Mac’s disk die, you can always boot up from the clone. Plus, both SuperDuper! and Carbon Copy Cloner have a built-in scheduler so you can set the cloning backup to a convenient time and it runs automatically, unattended.
And, after the initial backup, both apps backup incrementally, which means they only copy files that have been changed. That speeds up the backup process to a few minutes.
Finally, a word about backing up files online. Why online? A catastrophic or disaster could include fire, flood, theft, earthquake or damage sufficient to destroy your Mac and the Time Machine and clone backups.
So, critical files need to be copied to somewhere else besides home or office. That includes online backup services, a remote server, or CDs and DVDs (or even a portable disk drive) that can be stored elsewhere.