I think the secret is that you have to have a really good memory in order to pull it off. Remember what you told each person so that you will never get caught.
If you can't look someone square in the eye, then look at the end of their nose instead. (to the other person it will look like you are looking right at them.)
And remember to look to the right. Looking to the right means "recalling"
Looking to the left means "creating".
Try not to get to carried away with your story. If you toss in too many details, they may be hard to recall later should you have to re tell the story.
I mean, I've just heard al this stuff. I've of course NEVER tried it...