These days there is a ton of information out there on the ingredients to this dish: 1 part summary, outline your companies and positions with 3-5 parts accomplishment statements per job, throw in education, certifications and special trainings or interests - keep enough white space to make it digestible and don't let it simmer too long - not over 2 pages.

Outside of this formula or general practice - every career counselor or colleague might have an opinion about how to refine and write for optimal impact or readability, but whatever you write needs to resonate with you. You shouldn't forget the context for this "dish" and your key ingredient. The context is - what are you looking to do? The key ingredient is - what is your story? Especially if you have a 15, 20 or more year career with multiple jobs or companies, you can't, nor should you include it all in a resume. This should accent your salient highlights and the "so what factor" - what was the impact.

The resume is a marketing tool to tell your story - either to spark interest to get the interview or as a leave behind - "tell me more" -  after a networking meeting.Don't lose focus - the most important point is - does it tell the story - position your experiences and lead your reader to where you want to go? My statistics teacher in grad school always said, "the numbers know not what they say." We can massage and shape the numbers to create any argument we want. So too we can interpret and frame our experiences to tell the story we want to tell.Keep where you have been in perspective to where you want to go in light of where you are today. One gentleman has made a blog out of his job search experience in hopes of helping others, specifically targeted toward those over 50 - http://joewantswork.blogspot.com/.