I think most people (and hey, it used to work just fine, so nothing wrong, the rules just changed) think of a resume as a look back at the highlights of your past work and accomplishments you racked up. But the people who read resumes now - in this economic climate - don't care about what you've done, they are interested in what you can do for them NOW. That's where the keyword deal comes in. You need to look at all your past experience (paid or not) and see if you can find a way to apply them (shape them, mold them, fake them) to the new task/position you are applying for. Your resume should read as a point by point proof that you can do everything that they are asking for. Drop whatever is not relevant, no matter how much it pleases you, or how great an accomplishment it was. Target every one exactly to the ad. (I know, easier said than done).
For something academic I'd put my full educational credientials, program of study, topics, major professor. But if its' not that, then just putting down the top one does the trick, if I have a PhD, it's assumed I have a BA/BS somewhere along the line, i.e....
Education: PhD, Super Big State University, year.
If I'm applying for an office job is it necessary for them to know I have credentials to do full theatrical rigging? No. So I skip that, but put in all the computer stuff I can fit.
AND HAVE EVERYONE READ IT. everyone.