Federal resumes are kind of a dark art and can be very different from traditional private sector resumes. Those who say to turn in a private sector resume are misguided. I'm getting ready to retire from the military and a DoD mandate is that we spend a week in transition prep classes before we get out. That week includes three full 8-hour days on resumes, with a major focus on federal resumes. I've also written a few for family and evaluated a few as part of the hiring process.
The bottom line is the resume will be long -- much longer than you are used to, but that's OK. What you need to focus on is essentially building what is called a "master chronological resume." This is in effect a massive dump of every conceivable thing you can think of that you've done at every job for however far back you want to go, and all your education, training, certifications, etc. When people talk about updating your resume every 6-12 months, this is what should be updated. For a "normal" job you would then make a copy of this master resume and tailor it down to the 1-2 pages of only relevant info that nails that particular interview. This is how you can have one master resume that gets you in the door many places. The master resume is also the one you might hand out at a job fair or whatever, since it is general and not targeted at a specific job.
Generally speaking, a great federal resume will at the very top in the "objective" statement list the specific job ID you are applying for. That is the number for that job posting in USAJobs. It will then have a brief overview section hitting the main points of your qualifications, then a (possibly extensive) list of your previous positions, in reverse chronological order. Give a summary of the responsibilities you had at that job, then a list of bullets detailing specific accomplishments/impacts you had at that job. Then repeat until you have listed all your work experience. Note that "summary" can be misleading -- one job can take up half a page in this manner! After that you will have your education/training/certs and any other relevant info you need to add. Or you may put education before work experience, the order is not a hard rule, use whatever works better for you.
All that said, I think this is a great federal resume format that works very well. It is specifically a 2210 IT position resume so that should help you out. Note that it is incomplete, it cuts off after two pages because they want to sell you a service, but all you need is Word and about 40 hours of spare time to do it yourself. Seriously, I was told by someone who does this for $1,000 a pop that you should expect to spend 40 hours compiling and tweaking, but the end result is a professional summary of your entire career that you can add to every few months very easily. And that makes creating a private sector resume from it trivial. Also note it is dense, and again that is not only acceptable it is expected. That looks like about a 4-5 page resume in the making, and personally I really like that format and I've seen it a lot in the government, so it clearly works well.
Also, here is a great walkthrough showing you a 2210 job ad, then taking someone's existing resume and converting it into a beefed up format tailored specifically to that job. Notice the keyword bolding in the final resume -- that is actually a good thing, don't shy away from it. Write your master resume, then when you are tailoring it to the job ad you should interleave the keywords from the job ad into your resume, and bold or underline them. The federal government uses a giant centralized vetting system that evaluates candidates and ranks them based on qualifications, and then forwards the resumes of the qualified applicants to the local managers for evaluation. First the computer runs checks including keyword checks, so it ensures you pass that hurdle. Then a human has to evaluate whether or not you are qualified, and they have no idea what the job actually is and can only go by the description. So by bolding/underlining the keywords you sprinkle throughout the ad (truthfully of course, not randomly!) you make their job easier and you get through the second hurdle. Then you are that much closer to a call back.
This is the advice I was given, and many friends of mine have used this approach and it worked very very well for them. So hopefully the advice will help you too. Take care and good luck. :)
