I think they need to abandon "Returns" and start from scratch. Keep the title, keep "The Man of Steel" because it plays off of the Dark Knight, but... otherwise? Reboot.
The one thing they need most of all is a convincing Superman. They need someone with a mid-level large build. Not Schwarzenegger or the Rock build, but between Bale in Begins and Schwarzenegger in T2. Superman is supposed to be a little bulky, no skinny.
Likewise, the voice has to be right. He has to sound 30-ish. Not 18, like Routh.
Lois Lane needs to be a lot more sassy and smart, a lot less... Bosworth. LOL.
Avoid Luthor or make him supporting; do not focus upon him. They need a real villian. Doomsday, Darkside, Zod, somebody who can give him a true physical challenge.
If they want to do any origin stuff, do it like Begins did only quicker. Flashback/memory sequences as the story evolves. Even Superman's introduction to the world should be such. The film should begin with him fighting the bad guy, and go back and forth between such and memories.
Those are some really good ideas. Yeah the movie should be a total reboot, Clark arriving to Metropolis, finding a job etc while we get his origin in small flashbacks throughout the movie. Don't throw Doomsday at him in the first movie but definitely a real super villain and not Lex and his never ending supply of Kryptonite.
And yes they need a guy with muscles, Superman is a buff guy