For a contingency fee case, assume 33 to 40% will go to the attorney. And watch for the costs, as these will be in the tens of thousands of dollars. If you can get the attorney to front those fees, you should think about it if you have near term financial concerns.
Keep in mind that the very best medical malpractice lawyers can pick and choose the cases they want to try and you may be stuck paying the price they demand to get a top shelf med-mal trial lawyer. And that, quite frankly is the key. You have to find someone who tries cases and doesn't try to settle everything because the only lawyers that an insurer takes seriously in evaluating a case are those they know can win in front of a jury.
If you haven't done so already, I would try to find some local lawyers and ask about your prospective attorney's professional reputation. I would also find out if he/she is a member of the American College of Trial Lawyers. If he/she is, then he/she is in all likelihood the real deal. Also go take a look at the lawyer's biography at http://www.martindale.com
When you search for the lawyer's name, check the box next to the line reading "Search Martindale-Hubbell Peer Review Rated Lawyers." If your lawyer has been peer reviewed, his or her grade will be here. You want someone with an "AV" rating. Finally, call your local bar association and ask if the lawyer has ever been the subject of an ethics complaint.
The attorney is a member of the American College of Trial Lawyers. In my area, he's the real deal.
Thanks