As somebody's whose job it is to answer questions, I'm never short on advice, but you'll have to be the one to decide if it's useful or not! Although you indicate in your e-mail that you're involved with both AIX and Check Point stuff, your entire self-description concentrates on security or related topics. Thus, my reading of your inquiry is that you've already specialized in security matters -- at least, insofar as what you've shared with me. I think that recent industry trends and data validate security as a viable and still-growing field. I would recommend that you look into Check Point's various certifications (described online here) and perhaps think further ahead to something like the ISC2 CISSP (also described online here).
Other than that, assuming you're happy following that direction and want to stay in your current position, you'll simply have to decide how to transition from what I'm guessing must be a mix of system admin and security work to something more focused on security. If that means changing jobs, you may want to pursue and obtain some certifications first, unless you're prepared to present yourself and your extant security experience and knowledge in the most positive light possible.
For more info on this topic, visit these SearchSecurity.com resources:
This was first published in April 2004