I'm finally getting into simple PCB design for my personal projects, and I'm concerned about ESD protection on exposed parts of my board like USB ports. I know how wrist straps work and I understand things like clamp diodes on modern CMOS IC inputs (and a lot of articles I've found basically only discuss those things), but I'm more curious about discrete ESD protection devices. How should I choose them and use them? Any general tutorials that discuss the spectrum of devices and how to apply them? I have found some pretty good articles discussing how, for example, TVSes work, but in what situations are they an appropriate solution, why would I choose them over other devices, etc.