I know i'm not old, but I'm very familiar with his stuff, and I've seen him live twice.
In terms of getting to know his work, you're screwed, cause his work is pretty varied, but he has two sort of main styles, which are the grungy hard rock stuff and the acoustic singer-songwriter, country-ish stuff. The only album I can think of that has both of them and is amazing is Rust Never Sleeps, which is live.
The recent Live At Massey Hall 1971 is great, it's all acoustic and it has a lot of songs on it he had either previously recorded electrically or would later record electrically. It's really great. I saw him at Massey Hall last year by the way -the first time he had played it since that 1971 concert. Massey Hall is amazing, he was amazing.
Decade is a good one... two disc set of most of his best songs from 1967 to 1977.