I think perhaps this book doesn't really examine the issue in depth. For instance, my niece suggests that the first necessary step to hearing god's voice is to skip your meds.
I'm sure we could all come up with better ways than the namby-pamby stuff recommended in this book that would enable anyone to hear god's voice.
A very tight necktie, for instance.
Playing modern christian music backwards, while drinking Mogen David.
Instead of skipping your meds, in some cases it works better to double your meds.
Wear a tin-foil pyramid hat. No, wait a minute, that's for protecting your brain against the CIA. Ignore that.