Lots of good suggestions here, but the 'getting in shape' ones are probably the highest priority. Being in really good aerobic condition is paramount to having a good time, unless this is a different kind of elk hunt than I have ever been on. I have never hunted Oregon, but I was out there this summer, and the mountains are densely forested and steep, so the going will probably not be easy, although altitude is less of a problem there than in the Rockies.
I would also recommend a digital camera; they are compact, high quality, and easy to use. I gave up film several years ago after the quality of digitals became so good.
Practice shooting from odd angles; you may have to shoot around brush (or ferns in Oregon).
Have fun and enjoy the experience; elk are wonderful critters that live in awesome country. And, as you hopefully will find out, they are a whole bunch bigger than whitetails, so the pack out is a whole lot of work, unless you are lucky enough to have horses or the big bull dies close to your truck :D