It's crazy to think that Superman is almost 100 years old (okay, not quite, he was created in 1938...but he's GETTING THERE). With that much history, I don't blame any new comic reader for having a hard time figuring out where to jump in. There are a couple of great standalone stories that don't require much continuity knowledge to enjoy, so consider these books to be Level One, and then you can dig deeper from here if you like what you see.
All-Star Superman
Grant Morrison and Frank Quitely's epic maxiseries is complete disconnected from continuity and tells a timeless, weird, classic Superman saga with heavy doses of Lois, Lex, alien business, and all the things you'd expect from a foundational Superman story.
Kingdom Come
Whenever Superman disappears for awhile (or, y'know, dies at the hands of a giant monster named Doomsday), weird things happen. Kingdom Come finds Superman in exile following the death of Lois Lane, and tells the story of how the world has dealt with his absence. Brash young heroes have popped up, classic DC heroes have gone off the rails, and everyone's a little older...but what happens when Superman steps back into the fray? Has he changed too, or is it just the world that's gone mad?
Superman Birthright
In the grand tradition of "let's retell Superman's origin every decade or so and update some things," Superman Birthright is a 12-issue series by Mark Waid and Leinil Francis Yu that actually puts a new spin on the well-worn story. This is one of those books that doesn't get a lot of press, but comic fans often point to as a quiet modern classic. The Deluxe Edition hardcover is a beautiful collection that really highlight's Yu's breathtaking line work.
Superman: City of Tomorrow
This is a Mister Comic personal favorite. Right around the year 2000, the Superman books (there were 4 of them at the time: Superman, Adventures of Superman, Superman: The Man of Steel, and Action Comics) had gotten sorta creatively stagnant. So DC gave the whole line an overhaul and brought in some big name creators like Mark Millar, Jeph Loeb, and Ed McGuinness to make it all feel a little more modern for the turn of the century. The result was basically one giant weekly Superman comic, with one title released a week, and this era was meant as a jumping on point for new fans that did a tour through classic Superman villains and locations. They recently collected these in a proper trade paperback for the first time, and it's great!
Bonus: Superman's Pal Jimmy Olsen: Who Killed Jimmy Olsen?
Okay, so...this isn't TECHNICALLY a Superman story, but very few characters embody the spirit of what makes Superman great like his pal Jimmy Olsen. This 12-issue maxiseries from Matt Fraction and Steve Leiber takes Jimmy on a series of goofy episodic adventures that all tie together in the end. It's dense, frantic, and (like Jimmy himself) deserves its place alongside the greats.
These are just the tip of the Kryptonite! Check out even more great Superman family stories in our Superman collection.