I recall that Marvel has some kind of service for online backissues...
But then, I'm the sort of person who does not care too much about the minutia of most of what's gone before. I've gotten big into the Marvel Now comics, because the philosophy of those books is, "Everything that happened before still happened, but we're going to focus on what's happening now." Previous events are clearly relevant, in the sense that most of these characters are moving forward from them and are the people they are now because those things happened, but nonetheless reading the first issue of any given Marvel Now book (except perhaps Superior Spider-Man) is a solid jumping-on point for that reason.
(I've been recommending Marvel Now comics to friends left and right, whenever they ask for a comic they can get into and understand without a lot of backstory.)
If you are dedicated to learning the backstory...I think that the best encouragement that I can give is that precious little of it really matters, even when it's still in canon. Iron Man has been around since the early 60's, yes, but nothing before "Demon in a Bottle" and "Armor Wars" is terribly relevant to how the character is written now. (For that matter, I'd say that nothing between "Armor Wars" and "Extremis" has mattered much - that entire chunk of continuity may as well not be canon, because the character has moved forward so much from "Extremis" without a look backward.) Similarly, Geoff Johns, David Goyer, and James Robinson did a run of JSA that starts where it starts, and kind of assumes that everything before it is the stuff you'd not read closely.
The other recommendation is to get into everything that a specific writer has done for the character. Generally, you can find some specific writer who made a big mark on the series, and whose run can be read without much background.
edited 13th Aug '13 2:51:13 PM by TheEvilDrBolty
I'm aware that there are a lot of issues that the big companies have decided that everyone likes and that they should be kept in canon. And I would read just those before going on to the current series, but I can imagine a lot of them also require context from two other stories and then that story also requires context from three more and so on. It's a compulsion of mine, admittedly.
And then there's the trouble with some titles that have multiple iterations of a character or team, and I'm only interested in some of those iterations, but might need context from ones I'm not necessarily interested in and whatnot. It just seems kind of difficult to be able to do this without getting into everything ever, especially since that's what I want to do no matter how unrealistic it is.
edited 13th Aug '13 3:06:23 PM by DeviousRecital
Most modern comics have a Recap page that explains things you might need to know in order to understand what's going on in this issue. If Fin Fang Foom put Spider-Man in his pants over in Avengers and now Spider-Man being in Fin Fang Foom's pants is going to be relevant in DareDevil, either the recap will tell you it happened, or someone on-panel will explain what's going on. Comics are pretty good about helping newcomers with continuity these days.
I just got into comics a few years ago, during Marvel's Superhero Civil War, and the best advice I have to offer is this: make your peace with the fact that you won't know everything right off the bat. Reading everything that's ever been printed is a Sisyphean feat, but if it's important to the story you're reading now, it will be explained.
edited 13th Aug '13 3:11:03 PM by TobiasDrake
My Tumblr. Currently side-by-side liveblogging Digimon Adventure, sub vs dub.Marvel has their Marvel Unlimited
service. It includes access to 13 000 comics. It's $10 a month, or $70 a year. Those are actually pretty good prices, all things considered. There's a 6-month delay on new comics being added to it - perfectly reasonable - but you can also buy those new online.
But you really don't need to know the details. Anything you need to know for a given story will be explained in that story. If you really need more details, you can always look them up online. If you don't understand a reference, and you're curious about it, just ask someone on a comic book board, and you'll get a long and needlessly complicated explanation that'll convince you that you actually didn't need to know all that in the first place, and that you just want to go back to reading the story, dammit.
X-Men X-Pert, my blog where I talk about X-Men comics.I know, and the problem with all of this is that I'm the kind of person that prefers actually reading the issues in question rather than just a text recap in the comic itself or from some wiki or something. If it's important enough for me to know about, it's probably interesting enough for me to want to read it. I know how insufferable that is, and I apologize for it.
Granted, I didn't know that about Marvel. Shame the only Marvel titles I'm really interested in are X-Men, Daredevil, Dr. Strange and maybe Ghost Rider. That does sound like a really nice deal.
Well, nothing says you can't read just those comics on there. They've got plenty of history, especially the X-Men. Trust me, even if you read just the X-Men, you'll get your money's worth out of that deal.
If you do buy a subscription to Marvel Unlimited, might I recommend the 2009/2010 Strange Vol. 2? It has art from the incomparable Emma Rios - one of the best artists out there. Also worth checking out the 2010/2011 Osborn mini, written by the excellent Kelly Sue De Connick, with art by Emma Rios.
X-Men X-Pert, my blog where I talk about X-Men comics.I don't actually give a damn about DC, so I couldn't tell you. Maybe ask in the DC thread on here. I would imagine someone in there would know.
X-Men X-Pert, my blog where I talk about X-Men comics.

Comic books give me a headache. They really do. I've been trying to figure out some way to jump onboard for awhile now, but it seems neither DC nor Marvel is able to reprint their entire backlog. While this is understandable, it doesn't really satisfy me since I'm the kind of dumbass that needs to know every piece of continuity there is to know, even if it has since been undone by reboots. And that's not even getting into the financial costs or the fact that often one has to read a story from one book to get the necessary context for another, etc.
To make matters worse, I don't think I have a comics shop anywhere in my town and I can't find a website with proper scan uploads (if any even still exist), so how exactly is someone like me supposed to get into all this? Should I just give up hope and start buying New 52 stuff, even though I've heard the changes have been questionable, that most of the ones I'm interested in have been cancelled (such as Deathstroke, Hawkman, and the JLI) or else that I'd need prior continuity to understand anyway (Green Lantern)? Or is there anything else I can do?
And while I'm not as much of a fan of Marvel as I am of DC, I don't even know what I'm supposed to do with them. The bulk of their reprints aren't even in colour, and I can't have that...
edited 13th Aug '13 2:35:15 PM by DeviousRecital