Oh, well.
I guess you could grab pick up Spider-Man. They did this thing a couple of years ago that pretty much sets it up as a perfect jumping on point for newbies.
Hulk is supposed to do a new status quo change soon if they haven't done so already.
So, I'd start off with some trades.
Planet Hulk. Best Hulk Story I've ever read. Everything else with Hulk is a mixed bag at best. Red Hulk. Ugh.
Spider-Man. With Spider-Man you got Brand New day vol 1-3. Kraven's First Hunt, umm 24/7 and American Son, The Gauntlet and Big Time I guess. I can't tell you the quality of these because Spider-Man is dead to me. So These are the ones I've heard are good or whatever.
As far as Avengers. "Avengers Academy" is probably the best one. Spidey's on the "New Avengers" team.
Spidey is also a member of the FF and that is very good. Also Captain America, the Thor Related titles are good. But the main Thor Title Mighty Thor I think is hit or miss. Everything else is awesome. Daredevil is supposed to be getting a relaunch with Mark Waid on writing duties. That's all I got.
Right now they're doing this "Fear Itself" Event. (That's pretty much what superhero comics have become. Event, fallowed by that events fall out for a year, then another event.) Where Red Skulls daughter got powers from some old Asgardian God or something and now she's killin' everybody up in here and giving bad guys and good guys hammers that make them bad or more bad or whatever. Mixed reviews on that.