I'm not a JW, but I am intimately involved with one JW, my husband. I also have a history of overcoming tragedy, manipulation, and abuse.
If we can get them in time, I'd advise exiting JW's to have a plan before they leave. Sever their financial ties and other obligations with individual JW's. Set up a private bank account and start saving a nest egg. You'd be amazed how many live at home, work for another Witness, or in some other way are dependent on a Witness. This makes leaving doubly traumatic. Reduce the trauma of the event as much as possible, I say.
The second thing I'd advise them to do is start building a separate social network away from the Witnesses. A JW who leaves suddenly may still distrust "worldly" people and avoid them. This leaves the person completely socially isolated. I think the WTBTS depends on social isolation to convince "straying sheep" to grovel back to the society. It is a cruelty to shut off a person from all social contact. We're built for it, we need it. So prepare ahead of time and get used to regular people. It will soften the blow when you have to leave.
The third bit of advice, for the first year, is not to jump in to another belief system as "the truth". If you need a biblical reason for it, read up on the purpose of the Sabbath, Sabbaticals, and the "Year of Jubilee". Your mind needs a rest, away from too much outside influence. Read books outside your normal sphere, observe nature and other people, and spend some time absorbing what is real and true. Here are some books that made me think:
Education of a Wandering Man by Louis L'Amour
Flow: The Psychology of Optimal Experience by Mihaly Csikszentmihalyi
Becoming Human by Jean Vanier
...and for those who can tolerate self-help books,
Adult Children of Abusive Parents: A Healing Program for Those Who Have Been Physically, Sexually, or Emotionally Abused by Steven Farmer
This fourth book reminds me another thing. JW's are conditioned to take on all sorts of burdens that are not their own. They are guilted in to not disappointing their parents. They are told that the consequences of leaving (shunning, lost priveledges and status for parents) are entirely their fault. They seem compelled to tall sorts of personal information to the elders and fellow congregation members. The line of individuality and personhood is blurred. Many questions a JW asks is just plain rude. You don't have to answer everything. "That is none of your business" is an answer.
You don't have to meet with the elders if you don't want to. Elder meetings are never a fair fight, as they will never discuss a contentious issue with you without another elder present. If you balance the equation by bringing along a friend, they may cancel the meeting altogether. I've heard of so many cases where the elders have put their own spin on those meetings afterwards, and I can guarantee they did not make you look pretty. Why buy in to their whole judicial structure? Walk away.