What is one's best advice for a veteran wishing to gain employment with the DoD?

For Cybersecurity GIAC certs are key. A Comptia Sec+ isn't bad and can get you in most doors but the GSEC will help more as well as a CEH or CISSP look up 8570.01m and the IASE website for the baseline certs to start your career.

I see you have Sec+. As a former DoD hiring official I can say that getting a job depends significantly on your experience in Cybersecurity. A Sec+ is a start, but it is an entry level cert and is actually required for almost anyone working in IT, so it alone doesn't do much. Experience is a big factor in security, so if you don't have much you're going to need to get some.

You should apply for any IT job to get started building experience. It most likely won't be a cybersecurity job per say. However, all IT jobs are cybersecurity to a degree. After you get that job find the information assurance people in your organization and begin learning from them and volunteering to help with things. That is the fastest way to learn and also to be noticed as a "forward leaning" person who they may want to hire for a security position when one becomes available.

Oh, and the biggest thing to do when applying for DoD jobs is be willing to go anywhere. If you want a specific job in a specific location at a specific grade you may need to wait until people retire, and then wait some more. If you are willing to go anywhere in the world, then you have a lot more options. Especially if you are willing to take a job in a place no one wants to go.

There is no shortcut. You need to download the USA Jobs resume and shape your your information, loading it into the system after making an account. You then go through the search and save process within the site and save search for areas of interest that you are qualified for. You should also reach out to someone you know who has been successful and have them review your resume. Your resume must be reshaped (appropriately) based on the focus of the duties. Do not restrict yourself o DOD, there are many great Federal organizations that you may qualify for, DHS is a great example. Good luck in your endeavor.