Rule #1: Make regular backups of your critical data.
Rule #2: "Regular" is defined as the amount of time you can say "I can redo that work" without breaking into tears.
Rule #3: Back up critical files only. Don't waste time backing up your easily-reinstalled programs. Point your backup software at your data. That being said, only YOU know what is critical.
Rule #4: Backups take time. And reminders. Most are not automated so you'll need to discipline yourself to make backups as often (Rule #2) and of what (Rule #3) you require.
Options for backups
There are many options for backups, some enterprise, some user-level. This is a partial list.
Crashplan: Campus-sponsored service. For $100/year per 4 computers, you have unlimited backup space. Caveat: recovery of lots of small files can be slow. Best for small recoveries and not complete restores. http://kb.ucdavis.edu/?id=0383
Departmental Backup Server: We have a large backup server that mostly backs up the departmental file servers. If you're using the departmental file servers, your data is already backed up. For information regarding the use of the departmental file servers, ask Metro IT.
Time Machine: For Apple computers, an external drive and the Apple backup solution Time Machine is pretty snazzy.
Windows Backup: All Windows systems have a backup application built-in -- with an external drive this is a good option. Narrow your backup folders down to save time.
Third-Party Tools: Many external drives come with their own backup software. Read the description before you order.
Cloud Services: Box, Google Drive, OneDrive are all UCD-sponsored cloud storage services available for free to you. Be aware that syncing is not backing up but you can use all of the above services to back up your data to an area that does not sync. Just remember the Data Sensitivity Guide which helps determine what types of data can go where: https://cloud.ucdavis.edu/data-guide
Back up your stuff. Flash drives, cloud storage, Crashplan, external USB drives, email it to yourself, etc. But back it up. We have had several cases of someone who comes into our offices in July, has dropped their laptop, destroyed the drive, and has their PhD thesis backup from January. Don't be that person. Seriously, back your stuff up.