1. Use VPNs: One potential weak link in remote employee communication with back-end systems is the method they use to connect. Hopping onto the Wi-Fi hotspot at Starbucks or other open public network is looking for trouble. Using VPNs that require users to authenticate and connect through secure tunnels protects data in transit.
2. Use Strong Passwords: I know, typing in passwords to access your PC or email or files is a pain in the neck, but it's an easy way to prevent people from breaking in...unless you use "password" as your password. Be sure to mix up the capital letters and make it mandatory to include a number in there. Another idea is to follow the "something you know, and something you have" mantra. Not only require a password to log in, but something like a USB thumb drive with the appropriate software as well. This two-step authentication process ensures that even if someone steals your laptop and guesses your password (did you really think "123456" was going to work?), they won't be able to log in.
3. Encrypt, encrypt, encrypt: Hard drive encryption is easy with tools such as PointSec, Safeguard, and Safeboot. You can also choose to encrypt individual files to make it even harder for people to break in.
4. Protect Against Removable Storage: Whether it be a thumb drive, MP3 player, or smartphone, mass storage is cheap and easy to carry in and out of any enterprise. Software is available that prevents even authorized users from downloading files to removable storage. You can also choose to enforce encryption on removable storage if it is necessary that employees be able to transfer files back and forth. This way, only approved corporate computers can decrypt the information and access the files downloaded.
5. Beware of Your Neighbors: Alexander calls this one Shoulder Surfing. I totally agree with his point. In confined spaces, such as airplanes, it is often easy to view what people are doing on their laptops. Since you never know who you're sitting next to or in front of on an airplane, watch out. Buy a filter or screen protector that prevents others from seeing what you're doing. All too often I've seen people fire up company spreadsheets that may or may not have contained sensitive data and leave their laptop where others could see it.