A proper resume is 2 pages in length, and contains only relevant experience and credentials tailored to the position you are applying for. Even if the experience is in the same field, different employers require different responsibilities for a position.
For instance, a HRM at one company may do nothing but payroll. But at another organization, that same position might require the individual to do project management, payroll, counseling, and advertising employment opportunities.
In the former instance, the only experience they want to wade through to verify is your ability to successfully manage payroll. The latter will require you to tailor your qualifications to annotate experience in all facets of the position. Your resume will be different for every job and every company, targeting the specific organization and their needs - this helps keep it concise while providing them proof of your qualifications.
An electrician seeking a plumbing position would include construction experience and their knowledge of tools. It does no good to boast about running work, because being an electrical foreman has nothing to do with a plumber's apprentice. You mention it just enough to let the potential employer know you have been trusted with the responsibility, but elaboration means squat. Likewise, bending conduit, pulling wire, and motor controls shouldn't go on the resume... They have no bearing in the plumbing industry and only detract from the qualifications they seek. No one wants to muddle through a bunch of information to find pertinent qualifications.
The average time reading a resume is 2 minutes. You want them to see only the qualities best suited for the position in that time. That's what makes some resumes go to the pile that gets closely examined, while others are filed for later consideration. You want to be at the top of the pile.
I work very closely with an excellent lady at my college who has been writing resumes for 30+ years now. If you'd like help, shoot me a PM.
Also, go to this site:
www.about.comThey have tons of great information on resumes and job seeking, all for free.