Apple's Time Machine works in a funky way, so go over to your local store and get a large 4TB (or bigger) drive. Also, get Shirt Pocket's SuperDuper program, which will make a bootable external disk that replicates the internal drive in your system. In case something goes wrong with your internal drive, reboot your Mac while holding down the "option" key, and boot the backup. The newest version 3.2.5 supports Mojave and includes their Smart Delete, Smart Wake, and Smart Update features.
Charles wants to know the best way to set up Time Machine on his Mac with macOS Mojave. Leo says that in the new OS, there is a new APFS file system, and there have been backup issues with Time Machine and others. He may need to use an external drive formatted with the old HFS file system. That will insure that if his internal drive dies, his backup is secure. Leo also recommends not using Time Machine as his primary backup system. He should make an image backup with SuperDuper.
Lance upgraded to macOS Sierra and now his Time Machine isn't working. Apple Care hasn't been able to solve the problem either. He's even reinstalled the OS and Time Machine. It just hangs about 2/3 of the way through the backup. Leo says that nobody really likes Time Machine, especially when it doesn't work. No one really knows how it works, either. If Apple can't figure it out, it's a lost cause.
Mendota wants an alternative to Time Machine for backing up his computer. Leo says he's not a fan of Time Machine. He recommends SuperDuper because it can be bootable. Time Machine is a dumbed down, simpler backup solution "for the rest of us." But that ease of use is more dangerous because it's too easy to assume you've backed everything up and can restore it.
Vicki keeps getting notified about doing an upgrade to Yosemite. But being a private investigator, she's afraid to upgrade because it could break the software she uses. Leo says that's a legitimate fear. In general, if she's doing work on it, it's good to always be slow in performing major updates. She could consider doing it in between cases or while on vacation, perhaps. A major upgrade like that can break her software, or with a utility like iDVD, Apple may decide not to support it any longer and not include it in the next version of the operating system.
Dennis installed the OS X Yosemite beta on a separate hard drive, which has been working great. Now he wants to make a bootable image of his current Mavericks installation to a USB key. Leo says OS X has a boot manager built in, so he can hold down the option key while booting up and choose which operating system he wants to start up in.