Introduce a company style that the artists are forced to use! No individual styles, every character should look the same no matter who draws him/her, screw the artsy stuff. You want to draw in your own style? Create your own stuff at your own company.
Do a hard reboot, ditch everything, even the successful stuff, start over and don't look back.
Adopt the writer's room that tv shows have, hire 4 or 5 writers for one book, let them work together, throw around ideas, plan the storyline and then write individual issues with a head writer overseeing them.
The most important part: Make the books accessible! That's why getting rid of the shared universe and not having several book for the same character is important. Don't make readers feel like they need to read other books to get the full experience and don't crap on your writer's stories by forcing a stupid event on them every summer.
Do another hard reboot after five years, allow your current version of Spider-Man to end. Let him die (for real) or let him live happily ever after, let him go to prison after he snapped and murderd Norman Osborn or let him be celebrated as a hero after he proved himself to everyone. Having a set time before the next reboot allows for more interesting stories and it allows to have lasting consequences, you can kill characters off without retconning the shit out of the story 3 years later to bring them back, just wait until the next reboot.
Hi Takeru
I've edited the quotes, as I disagreed with some of your ideas and wanted to focus on those things I did agree with, hope you don't mind. I've felt for some time that we need to do a company-wide hard-reboot every few years for the exact same reasons as you though I would make it every 10-15 years rather than every five.
Also I disagreed with ditching the shared universe. I just think it needs to be handled in moderation without these company-wide extravaganzas every few months. If nothing else I'm running out of storage space

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Another idea you mentioned was ditching multiple titles for the same character. For more than a decade there were four monthly and 1 quarterly Superman titles and in essence this meant a Superman comic every week. During this time they introduced a numbering system known to fans as the triangle. It went Man of Steel, Superman, Adventures of Superman, Action Comics and Man of Tomorrow and it was one of the heydays of post war Superman comics. I still miss it. Now given your idea to adopt a common 'house style' for how the characters are drawn ala Archie Comics would perhaps do away with this if you had a Superman (or Batman) comic every week. But I am rather concerned about losing some iconic title if we go down your route eg Detective Comics or Action Comics.
I certainly do think though that 14 (or is it 15) Batman related titles is too much. There's Detective Comics, Batman, Batman and Robin, Batman Incorporated, Batman Dark Knight, Legends of the Dark Knight, Batwing, Batgirl, Batwoman, Catwoman, Nightwing, Red Robin, Red Hood, arguably Huntress, Birds of Prey.
If I'd been in charge of the new 52 I would have done a hard reboot and introduced a core of characters and titles building up over a period of a couple of years.
Anyway thats my two penneth.