The emphasis here is on figuring out how to carry the lightest load that will accomplish your goals, because there's not much fun in lugging heavy packs up steep trails. However, you are right that getting experience is really the best path to defining what you want out of backpacking and knowing what you need to get you there. So, there is a bit of a chicken-and-egg problem to overcome. That is especially true when one of your goals is not spending a huge wad of cash on equipment.

You can go a lot of places with cheap, crappy gear and still have a good time, and not coincidentally learn a LOT about what you want to replace with something better as soon as you can scrape the money together to do it. If I were rationing my cash I'd prioritize most of my spending on good sleeping bags and comfortable footwear.

The lightest things in your pack will always be the things you choose to do without. Extra clothes can make a pack very heavy in a big hurry and newbies almost always take more than they need.

If you've mostly been out during hunting season in the fall, be aware that the backcountry in Oregon in summer can be thick with mosquitos, espcially anywhere that has had patchy snow on the ground within a week or two of when you hike in there. About two weeks after all the snow is gone, the bugs die down to less epic levels. Deet helps.