I am also doing a Fed job search after a long time in the private sector. Here are some tips from my clients (who are Feds).
1. Buy this inexpensive e-book. It is very helpful.
http://www.resume-place.com/books/ten-steps-to-a-federal-job/. This website is also helpful in general.
2. Do NOT use your standard private sector resume. It is too short for federal HR people. Pick out the words used in the job posting and write to those in way more detail than you would have dreamed for a private sector job. Someone who knows me very well reviewed my resume and told me it would never get past HR because it was "only" 2 pages. My federal version is 7 pages (19 years experience).
3. Apply widely to get on "lists". If you get past the HR screening, they put you on "CertLists" that get passed around to hiring managers. So, even if a job is tracked for someone, you do yourself a favor by getting on as many lists as you can.