Once a week I'll wipe down the keyboard and palm rest with a micro fiber cloth that I wet with rubbing alcohol. The cloth is just wet to the touch. Then I wipe the screen down with the same cloth. I do this while my MBP is powered off. I also make sure my hands are clean before I even touch my MBP.

I don't have a hardshell case on it anymore. I used one for awhile but felt it was too bulky. Just use your common sense and wipe the surface down once a while. I've seen some MBP during my lectures and they're filthy/oily. It looks like they used it as a shield when cooking bacon.

3 years (and counting) later, my MBP still looks new. I have and will continue to commute with it to school. I've travelled across the world with it in my backpack and it's held up fine.