Nothing in your game has to change specifically to start playing Duplicate.
You'll want to change it gradually as you learn new things and become more skilled at bridge.You will rapidly become a much better player as you take up Duplicate.
You'll want to change some things as you see how they improve your play, defense and bidding. That's what this series is for.
(It's a gradual process-- we took about two years to learn to play Two Over One and all the conventions and systems in this book. Twelve years later, we play practically the identical system, but now we're Life Masters, using just what you'll read here.)
(c) Robert D. McConnell, 1998 All Rights Reserved