Bug repellent is a necessity, especially for warding off insects carrying diseases.
Sunblock!
When hiking wear sturdy hiking boots with good ankle support.
Carry or bring water everywhere you travel.
If going on an excursion of any type camping for a weekend or just an afternoon hike bring a small first aid kit.
If possible bring a cell phone, however, cell phone coverage is spotty in rural areas away from interstate highways.
Don't forget batteries - assuming that you are carrying something that uses batteries. A flashlight, maybe?
Tap water in Western Washington and Oregon is some of the safest in the world!
Be aware that the weather can change extremely quickly, so be prepared.
Crime in most Northwest cities is pretty low. Perhaps the highest crime rate of any city in the Northwest is in Tacoma mainly in East Tacoma, Hilltop and South Tacoma while the most dangerous neighborhood in the Northwest is the Rainier Valley neighborhood in Seattle. Other areas visitors should use caution in include Northeast Portland especially the King neighborhood, Seattle's Central District and Lake City neighborhoods, and White Center.
talk
English is the main language spoken in the Pacific Northwest and almost everyone living there speaks it. Some theorize that there is a distinct Pacific Northwest variation on language but most of the time people in the Pacific Northwest speak close to standard English with a few minor differences. Knowledge of other languages generally won't assist in this area.