I don't post much, but I am a long time reader & member of TechExams on reading various topics when I study for a particular exam. I admire the people on here whom study extremely hard and sacrifice many hours to learn & pass the exam with integrity instead of taking shortcuts. I sat the CCNA Security exam at Cisco Live with my free voucher received and was able to pass with a 908. Below are the resources I used and information that have helped me and will hopefully help you as well. Overall it took me 5 months, but I took it slow trying to absorb the material and by studying a little each day.
Cisco Press Official Cert Guide (outlined entire book and read notebook a handful of times)
Boson Exam Questions & videos that came with the book
Exam Cram 640-553 (Used if particular information was unclear and not found in press book or syllabus)
Sybex 640-553 (Used if particular information was unclear and not found in press book or syllabus)
Know CCP Well - Using GNU3
Cisco Exam Topics (Probably the MOST IMPORTANT) I performed a checklist crossing off each topic I covered. I can't stress this enough.
https://learningnetwork.cisco.com/docs/DOC-13753
Free Cisco Exam Questions to download - go through these and print them with the correct answers. Valuable, especially the VPN practice questions. The link below provides two valuable things. First is the weight of the exam topics of chapters you should be an expert in and second the topics that are downloadable you can check off as you go through the material.
https://learningnetwork.cisco.com/community/certifications/security_ccna/iins?tab=practice
To this day I am not thrilled with the exam question that Cisco test's you on. Hopefully that can be address one day in the near future by choosing more configuration questions than try to trick you. Either way read the questions very slow. If you can't understand the question, don't panic because every now and then you can find the answer within the answer by comparing your choices.
Taking a month break and will decide to pursue CCNP Route/Switch or Security...undecided at this time.