Things that should have been obvious to me when I first bought my iPod but which I've only now figured out:

(1) Don't rate music you don't like. At first I thought I should rate music I don't like as one or two stars. Problem is, I soon ran out of space to distinguish between tunes I really like, and tunes I really, really (or really, really, really) like. At first I was complaining that Apple should really offer half-star increments, then I realised that I just shouldn't rate bad songs at all. Preferrably, delete them from your iPod. I mean, you've still got them on CD, right? ;-) So you don't need to keep them on the iPod too unless you're a " total album experience" kinda person.