Welcome to the club, many days of luck to your hunting. I have 4 and 2 yr old boys that I can't wait to take out.
Great ideas guys, here is my two cents in a lot of detail to keep the discussion going.
Meeting someone, you are here on this board and I know there are several guys and gals from Oregon that would love to help out plus the above mentioned ways are great and going to the range with them is a must and then find out where they hunt. Oregon works off a lottery system I believe so there is no real open season.
I live in Washington and have buddies that to out of state and they tell me the regs are different so familiarize yourself with them. Different units have different regs etc... Go to the state web site.
Once you sit down with your new hunting partner see what type of hunting they do. Do they have a stand? Do they have a friend with property? Do they hunt state land? Do they move around a lot? Do they hunt all day? How many deer have they taken? Do they mind helping someone new?
As mentioned it can be a costly habit but when starting out stick to the basics, a plan, weapon, optics, knife and sharpener, food/water, clothing, and gear in about that order of importance.
First the plan, you should plan to have a great day in the field first off and foremost (there is a great thread about what hunting means I will track it down and post a link to it). It is called hunting, not killing. Just like it is called fishing and not catching. Once you know where you are going get a topographical map of the area, pre season scout (with your buddy if possible) but on your own too, this helps to get to know your area the terrain, roads, cabins, well used paths, etc.. prior to hunting, sometimes it helps in the actual pursuit of the game but they usually change habits once they hear the first shot, or rut has started so knowing where you are and what is around the corner is the main advantage. Make sure someone not going is familiar with the plan.
Your rifle brand will depend on fit and function. The caliber will depend on the number of rifles you want to buy, the game you seek, and where in Oregon you are going to be hunting. If you are hunting Eastern Oregon (open terrain) look into a .270 or something geared toward flat trajectory and long shots. If you are hunting Western Oregon a larger caliber shorter shots in heavy timber/undergrowth.
Optics are tricky and can be expensive. Look at posts depending on your budget. Start with a good rifle scope first shouldn't have to go over a 10 power and you can get away with a 30mm objective and then a pair of Binoculars. Go to a shop that has a viewing range or something similar. My local place is on the railroad tracks so they have a perfect 300yd range to see what works best for you. If that isn't available just read the labels on things across the store. You can spend more on optics than on a rifle.
Get at least one knife, heavy bladed drop point is my suggestion first off and have a way to sharpen it in the field. There is another post on gutting your deer once you have downed it, but hopefully your experienced hunting buddy will aid in this too.
Food and water, remember you are out to enjoy yourself so you want to be comfortable. Pack some protein bars, trail mix, or jerky and get a hydration pack to hold water and carry some of your gear.
Clothing, make sure it is quiet and comfortable and dress in layers because it is typically an all day event. You probably have enough stuff in your closet to get started without spending the dough on camo etc... Hunting here in the West is different than back East. Not as much preassure, and not as many people. I can suggest a good pair of leg gaiters is always nice.
Gear, keep it simple, man used to do this stuff in a loin cloth and with a spear. You can always pack too much so this reverts back to the plan, are you going to sit or move. I like to move so I pack light. Rope is a must, small first aid kit, matches, etc. in the event your plan changes and you have to spend the night, walkie talkies, different calls, grunts, rattling horns etc.. for when you really want to start scaring the wife. The list could go on.
Sorry about the length, I am already thinking of early morning sunrises, and the quiet before the bang!!!
Good luck and keep us posted.