Right now is actually an awesome time to jump into the X-Universe.
The 'five lights' story arc starting up in Uncanny is a great jumping on point for that book and doesn't require to much back story.
They just launched a new volume of adjectiveless X-Men that begins a huge vampire event in the X-verse.
A few new number 1's spotlighting individual mutants are on their way. Always good jumping on places.
Don't be afraid of not knowing stuff. Everyone at one point was completely lost when they jumped in the middle of a volume but its worth it with X-men.
I'd also suggest you look at some idie stuff. Just this past week a bunch of indie books hit with a number one. Officer Downe; Science-Fantasy from Image; Doctor Solar;
And don't be afraid to try new things that just seem interesting. Look at the creators, figure out which you like, and try something else they have done. The worst thing that can happen is you get burned by an issue. And that happens all the time even for long time readers.
I just reviewed Officer Downe and it's linked up on the site if your interested in that one. That's a One Shot comic though. But maybe a One Shot or an Annual is the way to go for now?
If your looking for some DC books to read, "Superman/Batman" (while not good and not bad) has stories that take about 3 issues to complete and don't require any previous knowledge of the DC world. Currently they are on the second issue of 3 or 4 in the current arc. If you're interested in more "Superman/Batman" stories, the direct to DVD movie Superman/Batman: Public Enemies is actually the first story from the title. The up coming DVD Superman/Batman: Apocalypse is actually the second story of the title that was called Superman/Batman: Supergirl.
Other than that, might I suggest comics based on video games. This way, you're already familiar with the characters and the plot and get things fleshed out for you. UDON is my personal favorite when it comes to this. They have Street Fighter, Street Fighter Legends (where the follow just 1 character), and Darkstalkers. Also out is God of War, but the last issue wasn't so hot IMO.
Point being, if you want to start reading something ... find something that you already know a little something about. If you watched animated cartoons, Batman Beyond just came out with a #1 issue. Tiny Titans (while targeted for kids) is an incredibly fun read for adults. A lot of people like Secret Six, Titans (book took a new direction and is only about 3 issues in), and the Suicide Squad because they're a team not bound by good or bad because they're all villains.
Flash just restarted as well. While he's not the best story in town right now, it's a great starting point and the art is very pleasant.
I'd say stay away from Batman until Bruce Wayne actually RETURNS.
Zatanna just started her own comic and is going to be on issue 3 next week. If you're into magic stories ...