I approach it with the same idea of a dress on a pretty girl. Just long enough to cover everything important, but short enough to keep it interesting. Problem is, when you’ve been in the business for a few years, it can easily turn into War and Peace . So, what I do is I go back 7 years (I figure if it’s good enough for the IRS, it’s good enough for everyone else - And my resume my can still weigh in at 4+ pages), and I focus on that UNLESS there’s a reason to go back further (like their looking for some experience that happened years before).
A lot of stuff that happened before that 7 years, I cover in the cover letter. I mention I’ve been in IT for 20+ years, and along the way I’ve done this, this and this (like being co-founder of an ISP, and having worked in Emergency Management, and so forth). I also direct them to my LinkedIn site for more information regarding me. This is also where I mention my being a Veteran, and so on
I always try to cut out the fluff. I can be very wordy, so when I write the resume, I try to cut out excess words and use bullet points to highlight what I’ve done (and if you can tie those bullet points into money saved or an increase in performance, even better).
I never mention hobbies and I never list references on the resume (I’ll give them those when they ask for them). Beyond the fact I went to college and have a BS (my degree isn’t in Computer Science), I don’t list too much education except to mention certifications, and that very briefly. A lot of that can wait for the face to face.
Last piece on the resume. Times change, styles change, so you have to keep it always and forever up to date. And for if you’re submitting resumes like crazy, and not getting any hits, go back to your resume and look at it. And give it an honest, hard look because that’s probably what your problem is. Just like we study Technical Material, you need to study how to write resumes and cover letters. This is a tool, and just assuming you know how to write one (or worse yet, have a tool that writes one for you) isn’t enough. Get every edge you can and treat it as a matter of survival. It is after all.