Landing a goverment job is pretty much all about location, perseverance and luck. Agencies get a windfall budget and hire like mad. Then they have no hiring budget for 5 or 10 years. For the past 3 or 4 years landing one has been easier than in the past. Mainly because all the baby boomers are retiring in mass. Your age will have no bearing on you being hired unless you want a federal LEO job. In that case you are out of luck because you have to be under 37 for those. From what I can see most young people have no desire to work for the goverment. The hiring process is too arduous and you have to have private sector experience to appreciate it.
The higher profile agencies like the FBI, CIA, IRS, NSA, DEA and such are much harder to get into then the ones that aren't as easily recognizable. Some like the FBI, IRS and DoJ people join for 2-3 years and leave for the private sector just for resume fodder or some kind of ticket there trying to punch. IMHO if you have both military experience and a bachelors, especially in finance, engineering or accounting you will be able land some type of federal.gov job. I believe OPM has mandated that all hiring take place from usajobs.gov, even if the position is off the general schedule like the Foreign Service. The only jobs where that may not be true is where you contact recruiters like if you want to be in the border patrol or a special agent with the FBI and such. Goverment IT jobs are notoriously hard to come by if you aren't already an employee of the goverment. It is usually where they move people who are having problems or are just tired of the position they were originally hired for. Like mountain biker said the closer you are to DC the easier it is to land one.
