Joeman,
I am originally from Northeast WA, and that is how I grew up hunting Colville Whitetails. Thick woods up there, some good agriculture in spots, same tactics you used in the midwest should produce for you.
For the rest of Eastern WA however, it is a lot of spot and stalk. Two things I learned quickly after moving to Walla Walla 8 years ago;
1. Get some good optics. Good binos, a spotting scope with a tripod tall enough to get you out of the CRP, and a good riflescope (I shoot a 6X18X50mm). Get the best ones you can afford. You are going to spend a lot of time looking through lenses, they are going to get a lot of wear, and so are your eyes.
2. Get a bipod for your rifle. I have found that if you are going to hunt the general rifle season here, a 200 yard shot is the norm. 100 yards is a gift. With my .270 shooting 130 grain Federal Premiums, I sight in 2 1/2 inches high at 100 yards, that puts me dead on at 200 and about 3 inches low at 300. I use a Versapod because I can take it on and off my rifle by flipping a switch, it swivels easily and the legs are long enough to get my scope above the prairie grass.
Good luck. This is a good time of year to get out there and see what survived the season and will be available next year..