The real question is: "how did I find myself in the Forest Service?". My current job i got working up the ranks in said dicipline.
The the real answer is: college career center. I was looking for options for my "capstone" experince and wound up doing a summer internship for the Pike National Forest as a Motorized Trail Crew Member. Once you are in the system and know how the systems works it is easier to start moving forward. USAJobs is a decent place to peruse, but still in my mind if you want a job it is best to do a face to face with the person you want to work for. It builds credibility and recognition when the hiring person can put a face to a name whilst looking over hundreds of apps. Food for thought. Granted some hiring processes these days have removed the final decision from the hands of the person who really needs to have the final decision, or at least some input. But that is another topic. Cheers