Using the "cloud" means you are renting space on a remote server.
Search "personal cloud space" on your browser for up to date info on cloud services for personal use.
Common cloud providers include (as of April 2013)
... and many more
1.) Save *only* what is important to you.
No need to spend your time preserving files you don't even need.
Take a moment to get rid of what you don't need.
2.) Back up multiple copies of files & check on them.
Set your computer to automatically back up certain folders to an external hard drive and/or to a storage space in the cloud.
Flash drives can also help serve as a back-up if monitored and replaced over time, such as yearly.
3.) Name & organize files.
Imagine someone else trying to make sense of your files.
Organize them into logical folders and given them meaningful filenames
(for ex., not "agenda.doc" but perhaps "gardenclub-agenda-2013-01-25.doc".
4.) Migrate & refresh files when upgrading software.
For example, when you move to a new OS (operating system, such as Windows 7) or are updating software such as Microsoft Word or Pages, re-save your important documents in that environment.
5.) Save in stable formats such as pdf or txt.
Non-proprietary formats are a safer long-term bet than counting on any particular software company to stay in business and continue supporting its formats.
If you don't need to contiually edit certain documents, but want to save them, choose stable formats such as pdf or txt which don't require much digital-babysitting.
Additional info:
Library of Congress' tips: http://www.digitalpreservation.gov/personalarchiving/records.html
File naming is very important!
Specific filenames that tell you what the file really is help prevent accidental deletions or overwriting.
Tutorials: