Depends, are you talking my first child or my second lol. I'm more a digital archiver now. In the beginning, I kept these large bins with school work. Eventually, I went through them all. I scanned in and burned my favorite artwork, stories and classwork onto DVD. I only saved a handful of hard copies along with 1 elementary journal per grade (they would fill a journal a month so could hardly keep them all!) Each has a bin and it's marked with their name and what it is. I don't stress about the archival quality boxes. Most are expensive and not water-proof. Besides, most of my kids stuff is stored digitally too.
Each child also has 2 scrapbooks (old-fashioned kind, not the fancy scissor kind.) One is for theatre because they do several plays a year. Each show gets a program, a ticket stub, a check stub if they got paid for it, a couple pictures, newspaper clippings, ect. I try to keep it down to 2 pages a show but there are a couple that have more, some that just have 1. Each child also has another scrapbook that holds all the other stuff... award certificates, ribbons, karate events, school talent shows, team pictures from sports, picture of child with trophy, orchestra programs, special honors or activities they participated in. I try to stick to the same "on page per event" and always include a picture with it. I also scan in these items so they are available digitally. The kids love to look through the books and it's nice to have something all laid out and easy to look at. That's the problem with the bins, they aren't particularly accessable but since I don't want any more furniture in the house, the bins are good for the garage.
My long-term advice, go through the stuff every few years. It's really, really hard to give up all those preschool pictures when they are 4 but when they are 13, it's much easier to narrow it down to 3 favorites. You sort of have to otherwise you don't have room for all the stuff they've done since that you aren't ready to let go of yet lol.