I took the CCRN last year at this time. I started studying for it the moment that I decided I was going to take it. I studied with others in my unit that I convinced to take it with me. Since I don't work in ICU, I took every class possible that my hospital offered (i.e hemodynamics, ACLS, etc).
For books I bought the three book deal from Amazon
Pass CCRN, Laura Gasparis Vonfrolio's Book, and another book that I can't remember. I also watched Laura's workshop review videos.
offers some of the excerpts of Laura's book under the critical care section.
Best thing that you can do is have a positive can do attitude and feel good when you pass!