(1) We still use tar
Back up with tar. The old ones are the best, and a full backup of your home directory with tar is easy to do and easy to restore from. Put it on a USB stick, external drive, cloud server, or just another computer and you'll always have a safe copy of your precious data collection
(2) RAID your drives
A RAID array won't be of any use if you accidentally delete some of your flies, but it will offer you some protection if your hard drive fails. Most distros can set up RAID when you install, and a second hard drive is a cheap investment, at least on a desktop. And, as a bonus, it can improve your machine's performance.
(3) Security after the event
With increasingly sensitive data being stored on portable devices, especially smartphones, there are more reasons to protect them and lots of different ways to do it. Apart from the obvious use of passwords and PINs, there are services such as Prey (http:/ / preyproject.com) that can be used to track, shutdown, lock, or even wipe your device should it go AWOL. Prey can even use a laptop's webcam to take a photo of the thief and send it to you when they go online.
(4) Sync your computers
Use Unison to keep your laptop/netbook and desktop in sync, or even your work and home computers. Not only does it provide you with a backup of everything, it also means you never suffer "the file I need is on my other computer" headache. Get into the habit of running Unison before you leave or shutdown a computer.
(5) Beware the cloud
Cloud storage can protect your data from local hardware failure, but what about prying eyes? It's not enough for the company to encrypt your data, if it can decrypt it to send to you, an employee can read it. Use local encryption for important data.
(6) Experimental file systems
It can be fun to experiment with new file systems such as Btrfs. but don't use them for anything important until you trust them completely. Use a separate partition for data that is either disposable or can be recreated, such as your collection of CD and DVD rips or for your experiments, and stick to the reliable standards for the likes of / home.
(7) Cloud backup
There are many options for storing your data in the cloud: Gmail or Flickr, for example, for mail and photographs respectively, or Dropbox for just about anything. Some services are free and that means you get the guarantees of service that you pay for. It's also important to remember that your data is on someone else's computer- if it contains anything private, encrypt it. And use decent passwords, both for the service and for the encryption.
If you have a laptop or netbook, you really should use encryption. Ubuntu can use eCryptfs to encrypt the contents of your home directory, while other distros have options to encrypt the entire hard drive. The effort it takes to decrypt it all, even on a modest netbook, is far outweighed by the reassurance that no one else can log in to your bank account.
(9) Beware the actual crash
Protecting your laptop from theft is important, but don't forget the risk of accidental damage. A decent protective case or sleeve for your machine could mean the difference, if you drop it, between a computer and an expensive paperweight.
(10) Schedule backups
Backing up is one of those things you were just about to do when everything went wrong. Don't rely on your self-motivation; use a scheduled backup program (or even a Cron task) to do the job for you. It won't forget (as long as the computer is switched on), won't decide to watch one more You Tube clip or have another cup of coffee before getting round to it. In short, software is more reliable than you are.
(11) Should you trust Gmail?
Not that there's anything wrong with Gmail, but you are giving Google permission to read all of your emails, and that's what Google does best - reads other people's stuff and makes it available in another form to its customers. Other webmail services carry similar risks, but Google is best at it, so if privacy is a concern, keep your mail local.
(12) Off-site storage
Keeping backups of your data on a DVD or an external drive at home will help if your hardware fails or in the case of a 10-Ten-T error, but they'll be no use if your home or office is physically damaged. Offsite backups, even if not as frequent, are good insurance. Cloud storage is one option, or you could leave backups with your family - anywhere far enough away to be safe, but near enough to be useful.
(13) Create extra users
Do your family or friends ever ask to use your computer? If you let someone else loose on your machine create an extra user and make sure they use that identity when they log in. It avoids the risk of them deleting, or reading, something they shouldn't. It also avoids them accessing your Facebook or Twitter account via your browser's automatic login.
(14) Image backups
When you intend to do something major, such as install a new distro, use a disk imaging tool, such as Partimage or Clonezilla, to make a complete disk backup. That way, if you don't get on with your new distro, or it doesn't get on with you, you can go back to the way things were. After all, some people like Gnome 2!
(15) Encrypt and sign email
You wouldn't send private information on a postcard, yet email is sent as plain text, via whatever servers are deemed necessary to get it to its destination. It can be read at any point on its journey, unless you use encryption to make it unreadable and digital signing to ensure it has not been touched. This may be OTT for your subscription to your local LUG mailing list, but not for financial or business correspondence.
(16) Viruses are real
Are there any serious viruses for Linux? No. Does that mean we can be complacent? Of course not. Apart from the threat posed by Windows viruses on dual-boot systems, there have been enough 'harmless' Linux malware examples to illustrate that it's important to be aware of the risk. Don't fall into the trap of thinking that permissions will protect you from a virus that runs as a user - userspace is where all your really important data lives.
(17) Use an external drive
Hard drives are cheap, memories are not. An external hard drive is a wise investment to preserve your photos, videos and music -- as long as you remember to copy everything to it and keep it somewhere safe.
(18) Don't leave it on a train
UK government departments seem to make a habit of leaving laptops and hard drives full of sensitive data on trains or in coffee shops. Amazingly, they seem to manage to walk away with their wallets and their keys, though, so the solution is simple: be more careful. Or use one of those Bluetooth gadgets that beeps when you walk out of range.