Security
Hardening is the process of securing a system, and I think it should be the first topic to approach.
It is a good idea to have a secure approach every time you need to provide some service, be it available only to trusted clients, or available to anyone. Locking things down as much as possible before can save you from headaches after.
Firewalls might not be a panacea for all the security risks a networked host can face, but they are a real good mean of protection and policies enforcement.
TLS/SSL is a good way to add an encryption layer to your communications. Most services support it, and in the end it is not that difficult to setup.
Whatever you use a laptop, a pen drive, or you are really concerned about the confidentiality of your data, encryption can be really useful.
