Reading 'Handling the big jets' is a start, but no substitute for experience. Simulator upset training has value, but again it's not like being in a real aircraft acheiving more extreme attitudes.
I'm sometimes suprised by the fact that many of my colleagues with tens of thousands of hours have never seen an angle of bank over 90 degrees. Having been bought up on a diet of visual and IF UPs (unusual positions) both as a student and an instructor in the military, my advice to those who haven't tried it is to go out there, find a school with an aerobatic aircraft and go and enjoy yourself for a few hours. You owe it to yourself - amd your passengers! What's more, you will become a better pilot and make yourself just that little bit safer. As a long time Airbus FBW pilot, I'm aware that my skills have been dulled down over the years. I make sure that I stay in touch with real flying by doing a few hours of 'real' upside down style flying each year.