1. Current experience
Whatever experience you have that involves the newest technologies or products, put that first. Emphasize that. Nobody gives a shit about Netware or DOS experience anymore. If your experience is dated by more than 5 years, download trial versions, white papers, buy books, watch YouTube videos, whatever it takes to at least say (with honesty) that you are at least familiar with newer stuff.
Keep this in mind: with a sucky economy there are a lot of unemployed skilled folks looking for work. You need to stand out more than ever. Technology is all about change and adaptation and improvement. Show that you fit with that concept as well.
2. Spelling and Grammar
What can I say? On average, out of ten (10) "professional" resumes, five (5) will contain spelling errors, some will be horrifically bad. Seven (7) of them will contain grammatical errors. Know your vendor names, product names, and acronyms. Be able to rattle off what the letters stand for as well. What does "CAD" stand for? It's "Autodesk" not "AutoDesk" or "Auto Desk". There is no "AutoCad" or "Auto Cad", it's "AutoCAD". The vendor isn't "AutoCAD". That's a product name. Trademarks are a serious and expensive matter. They cost millions to establish and protect - act like you know that. If technology is your chosen profession, know your shit.
Resumes with gross spelling and grammar issues are rejected immediately. No further reading required.
3. Systems, Products, Technologies
Provide a concise list of what things you know and are good at managing. Specify how you are familiar with each one. Installing? Customizing? Administering? Supporting? Include version numbers and years of experience as well. Most importantly, exclude things that don't relate directly to the position being applied for. Management positions might involve experience gained from managing a softball team, but most data center and help desk positions don't give a shit about things like that.
If you have a long list of things to claim, it might be best to put them on a separate page.
Most important: If you put something on your resume BE PREPARED to discuss it in depth. Most worthy IT managers will run through everything you state during your interview. If you stumble or appear lost it will scream "liar!"
Provide brief summaries of important projects, what your role was, what products were involved and what benefit it provided to the customer or employer. The general rule of thumb is the higher the level of the job being applied for, the more emphasis on cost savings or process improvement. But be careful to leave out the James Mitchner prose. Keep it concise and focused on the facts.
5. Depth and Detail
Leave out the fluff. MBA folks can handle fluff. IT nerds HATE it. It infuriates them. It's a garanteed opportunity killer. Don't tell a story unless you are applying for a position called "Storyteller". Facts. It's all about the facts. Have your resume reviewed by at least two other people who work in the same field. The more the better.
Basically, read it yourself and ask if you would believe it and would you hire that person.