Appropriate subject matter for a sketchbook?

[Ashtonw]

I've heard sketchbooks are helpful when applying to art schools, but what do you put in them? Nice, neat drawings from life? How perfect does everything have to be, because the sketchy doodles in my previous sketchbooks haven't always been attractive and you're only supposed to put your best work in your portfolio.

[Meloncov]

Don't stress about it. It's fine if some of the stuff isn't great, or isn't on the subject that they'd like your main pieces to be focused. Just try to have some variety.

[Mirana]

Except that it's understood that it's your sketchbook in which you're studying and working things out. Drawings from life are probably best, but I wouldn't worry about throwing in your sketch process for concept/illustration/comic/etc work. I had both in my personal sketchbook that was shown spur-of-the-moment during a portfolio day and got lots of great feedback.