My suggestion is to get a pouch that holds your iPod and earbuds, etc. A pouch or container for your pens, pencils, etc. Etc.

I find my "stuff" much easier to manage when it's in smaller pouches which I can then move from one bag to another easily, and can quickly spot when I need something. I've tried bags/attaches that have compartments built in and found them more trouble than they were worth. I usually had trouble figuring out the best configuration for putting things, and rarely remembered where things went so I ended up tossing stuff in loose and then hunting.

I'm particularly pleased with the notebook sleeve and iPod gearcase I got from WaterField SF Bags.

As for which type bag -- that depends on what is comfortable to you. I carry a much heavier bag than many people are comfortable with because I do tend to carry everything -- my laptop, iPod, camera, etc. I found that messenger bags are awkward for me, but bags that are vertically oriented are comfortable. I also don't mind shifting my bag from one shoulder to the other if it gets heavy, which I've discovered some of my friends consider to be a major negative.