One way, that worked for me is:
1. Talk about apostates with them. Ask them about their feelings for apostates. Are all apostates evil? Ok, but those who where DF:d for going to the police when they were molested or beaten? Are they really evil too? Ok, if they are not, there can be some exceptions...
And when they know that not all apostates are "evil", you are ready for step two.
2. Ask them if they know who Raymond Franz is? They might know he is an evil apostate, then tell them that he left Brooklyn himself. He even got 10000$ for doing so. Tell them that you don't know why he wrote that book, but there might be some truth in it? No? Then tell them that some topics in that book can be checked, they are true, you can check them with WT-articles, tapes and meeting protocols.
Of course I know that he only wrote that book to earn money and he was angry with the organization, but still he was in the GB for 9 years? Did you know that he wrote most of "insight on the scriptures" (or at least "aid to bible understanding", but they are pretty much the same) and that he has a lot to do with the things that today are presented as part of the truth?
When you have gotten them to think that maybe he is not so very evil, just was a little uncertain on the present truth then, and he very likely would not have left today (we are stretching the truth here, it's called theocratic war strategy with a fancier name), then, you are ready for step three.
3. Now ask them if you can read just a little part of his book? Nothing that will say anything negative of the organization, you just want to read about his life before he entered the GB.
And after that, maybe you can read a little part about how the GB works? at this stage, you simply jump the parts were he gives his own opinions about the bad things.
And now, when you have read a part of the book, wouldn't it be interesting to hear a little more? As you see there is nothing in here that is negative to the organization. The only faults you have heard of this far is surely better today in the truth. Of course.
When you have agreed that the book might contain some harmless or anyway not devastating facts about the org. , then you are ready for step 4.
4. Now you just read through the chapters, only skipping the parts were he (Ray) gives his own "negative" comments to the text. They don't wanna hear it but they agree to listen to you, because you are sure all these faults are corrected today in the truth.
When you have read all the chapters, except for the starting "personal thought" ones and the ones in the end dealing with his own case, you are ready for the final step 5.
5. At this point, the game is over. No more excuses, no more Mr. Nice Guy. You just feed them with the "right food in the proper time". Going through things like the 607 b.c. destruction of Jerusalem, the two witness rule, misquotations and deliberant lies in the literature , the embarrassing history etc. etc. etc.
And now, it's all up to them, of course they now know about all the errors and stuff with the organization, but they still believe that the org is Gods channel and pet on the earth.
You just give them time, and continue feeding them with food "at the proper time" and eventually in the end, there eyes will open, hallelujah !