Welcome to the danger zone!
As soon as we plug the PC into the wall, into the global network, we're in no man's land. Flying malwares fill the air, and however much we have secured the network locally, we and our data are in the line of fire, and susceptible to social scams and zero day attacks.
And that's just on a trusted machine. The threat level redlines when we're out and about, sharing PCs and hot-spotting wireless connections.
Let's prepare for and strengthen these weak links and, while we're about it, lock down the browser and chain up our mail. Here are the marching orders: