Lesson: Bear Spray
When Montana-raised Ryan Dorn first moved out to Washington, he was surprised by the absence of bear spray as one of the hiking essentials. "Back in Montana, everyone carries bear spray any time they go out on a hike. In fact, lots of people just carry it around at all times. You just never know when you're going to see a bear."
While we may not have bears rubbing their rears on every other tree around here, they are most definitely out there, and bear spray can come in handy if you knowingly enter an area with recent bear sightings. The spray itself is non-toxic and non-lethal, temporarily affecting the respiratory system and mucus membranes (note: don't use on yourself or your friends). What's in the magic potion? A nice blend of Oleoresin Capsicum (oily hot-pepper residue) and aerosol to give it the push. The stuff isn't cheap, but it could save your life.
For more bear safety, check out this (nicely put together) bear safety guide by the National Park Service.