Well, if you're completely new to DC, I suppose you check out the DC Nu; I have an alternate though. You see, there was a time myself when I wasn't to familiar with the DCU either, but I was able to find an accessible and very enjoyable way in; the DCAU. True, it's not the actual comics, but it captures the spirit of them, and also lets you get to know many of the characters, locations, and various other things among them; you also don't have to bother with past continuity or Crisis Crossovers, and can just sit down and enjoy them with no problem; they're also just plain good on their own, especially Batman TAS. It's how I got into DC, and I think it can work for you too.
Now, if you want to check out the actual comics, I'd recommend the following;
1.Crisis on Infinite Earths: The first Crisis Crossover conceived, and still one of the greatest and influential to this day. Aside from having changed DC comics forever, (including not just getting rid of the Multiverse for 20 years, but also countless other changes, such as radically altering Superman's history, and completely rebooting Wonderwoman's,) it's also a good, epic read in and of itself, and compared to some later Crisis Crossover 's, there isn't as much knowledge of the DCU required.
2.Grant Morrison's JLA: Now, I personally don't think this is as great as some people think it is. It's by no means bad; the plots are creative and quite epic&grand in scope, and it's all about the big guns (with 7 or 8 other characters as well,) teaming up to face these epic plots. However, the run expected you to have already gotten to know these characters, or picked up their own books as the time of publication, so there wasn't a whole lot of characterization or focus on the characters. Still, if you're looking for some League, this is by no means a bad option, and it's still a fun, wild ride.
3. Kieth Giffen's JLI/JLE: This is the polar opposite of Morrison's JLA. Whereas that run focused on big epic plots over characterization, JLI (Justice Leage International,) focuses on characterization&humor over big epic plots; whereas Grant's JLA was about getting the big guns together, JLI — whilst still having a few of them, such as Batman&Martian Manhunter, and the Flash (Wally West,) in JLE (the spin-off series, Justice League Europe,) it focuses much more on characters that, prior and partially since to this series, were less important or even minor characters. However, the humor and characterization of both series pulls through, with part of that being that since most of these characters didn't have their own books at the time, all of their development had to occur within these two comics alone. All in all, if you're looking for big epic plots&action, go for Grant's JLA, but otherwise, JLI is great in it's own right, and personally, I like it better myself.
4.JSA: The JSA was originally DC's first Super-team, back in the 40's&early 50's. By 1999 however, they were all but defunct, until in that same year, when they were given their own new series, combining a few of the old members with many newer characters; the result was one of the best DC comicbooks to hit the shelves in the last decade. It not only has some good, sprawling action, but the characters get equal attention, developing well over the course of it. There's also a keen use of subplots, and — well, I could go on and on, but the point is, it's a good series. Just an FYI — you may have to pick up Infinite Crisis after Volume 11 to understand some things for later; Hawkman Omnibus vol 1 is also good for fleshing out Hawkman, and Hawkgirl too to an extent. (They're members of the team.)
And that's all I have for now. Hopefully, you'll find something that works for you.
edited 15th Jun '12 9:36:29 PM by kkhohoho

I'm a big Marvel fan, but I want to start getting into DC. is the beginning of the reboot the best place to start? Or are there stories people would recommend prior to the reboot? Thanks!