Instead of lying and as part of the extensive preparation you are doing, you must sit down and anticipate the awkward questions you are likely to be asked.
Preparing a set of glib answers very rarely works and will do your profile no good at all. Interviewers see through this practice very quickly and to prove their point will continue to throw tough questions at you to see how you will respond.
Preparation is the key to formulating effective answers, if a question proves difficult at interview it is probably because you did not prepare thoroughly enough.
You will never be able to predict all the questions you may be asked however do some role reversal and place yourself in the interviewers shoes. Try to predict the type of questions they may ask, the majority will be around the job requirements as they determine if you have the necessary skills and experience to match the position.
They will ask for details on your previous roles, reasons for leaving, career aspirations and what contribution you can make within the new position if successful. Develop a series of questions based around these and practice until you have the ability to answer your practice questions with confidence.
Thorough interview preparation should not be dismissed as a myth, it is a far more effective way to spend your time as opposed to making up or memorizing answers in anticipation of your interview.