Many a time when you are connecting to a wireless internet, there may chances of getting your information or data steal by any unauthorized user. You have to make sure all your data is secure while transferring it over the internet, always have firewall installed in your laptop and keep its setting to restrictive. Also turn off the file sharing and other services like the FTP. When you leave your laptops for some time have a login and password to the laptop to avoid unauthorized access.
Also, keep your important data in the encrypting format on the disk if in case of theft. Keeping your data in the encryption format will not allow your data to be readable. While you are transferring any data over the internet you can encrypt your data to keep it secure.