Use Apple's MobileMe Backup app to back up important data
Apple has a seemingly secret app: MobileMe Backup. Don't let the name fool you, though; MobileMe Backup will actually back up pretty much anything and everything on your Mac, but there is a catch.
If you had a MobileMe account before the transition to iCloud, you may have heard about the MobileMe Backup tool.
The app, made by Apple, still requires a MobileMe account to unlock the full app; it backs up your personal data and information on a custom schedule.
The good news is, if you did have a MobileMe account (or still do if you haven't made the transition), you will be able to use the full app. If you didn't have a paid MobileMe account prior to iCloud, you will only have access to the trial mode of MobileMe Backup, capping your backups at 100MB.
The 100MB doesn't sound like a lot, and in fact it isn't, but it should be more than enough to back up some of your most vital information. With the release of iCloud the chances are that Apple will eventually phase out this handy app, but it shouldn't stop you from using it right now to ensure your data is always backed up should anything go wrong with iCloud.
Download and install the MobileMe Backup tool, which can be found in an Apple support document.
After it's installed, you can set up a backup plan by clicking on the + sign.
If you had a MobileMe account and have full access to the app, you aren't limited in the type of backup you can set up. If you are locked to the trial, whatever backup plan you decide on, make sure the total size of the backup does not exceed 100MB. You more than likely can back up your Personal Data & Settings and not exceed the 100MB size limit.
If you decide you want to create a custom backup, the options are more or less endless. You will be presented with some predefined categories, or you can narrow it down to a specific file or folder to back up.
After you have selected the type of backup, you will be presented with a list of all the items to be backed up, as well as the total size of the backup. If you selected your personal data to be backed up, you will see that the app defaults to iDisk, which is fine if you were once a MobileMe subscriber (even at that, eventually iDisk will no longer exist).
To delete iDisk as the backup destination, click on the iDisk icon and delete it from the destination portion. Clicking on the + will allow you to designate the new backup destination. You can back up to anywhere on your Mac, or even to an external drive.
You can get as creative as you would like with backups. If you need to restore from a given backup, launch the app, select the Restore tab, and follow the prompts.