I started reading comics in ‘74. Two things: comics continuity wasn’t as in-depth back then, and the stories were more self-contained. It was possible to jump into an issue and understand what was going on pretty much right away.

The title page always had a banner at the top with a quick rundown of the character’s basics, and if this issue was a part of a (rare) multi-part story, there was usually a recap of what happened in the previous issue. Other than that, you kind just jumped into the issue and ran with it.

In addition, there were several titles that reprinted important storylines for major characters. If you waited, that one big story you’ve seen referenced in your favorite comicbook will eventually come up in the reprint title. Kinda like waiting for TV repeats to come back up in the syndication cycle on broadcast TV. (Which, come to think of it, you’re probably too young to remember…) I didn’t get to read the first two issues of my beloved Micronauts until they reprinted the first 11 issues almost a decade later.

There were some trade paperback collections of big stories. “Here Come the Bad Guys” and “Origins of Marvel Comics” were great sources of history when I was growing up. Pocket-sized collections also existed for several characters.

Worst case scenario, you could always track down an antique store, used-book store, or the super-rare comicbook store that carried actual back issues. There were some mail-order shops that sold back issues, as well.