I've worked in the legal field for over 20 years. The 50% lawyer fee is rather high. Most charge 33-1/3% or 40% and it goes up from there depending on whether it goes to trial or goes up on appeal after the trial. What you need to inquire about is the costs. You will probably be charged for copies, color copies, faxes, postage, long distance phone calls, parking, courier fees and on-line research services. Discuss these items with the attorney and possibly negotiate a lower rate for at least the copying. You'd be surprised how many photocopies are made during the litigation process, which could take up to two years to go to trial. Some firms are starting to charge for every page printed off their computers, too. Make sure you get a written fee agreement and that everything is spelled out for you.
In most civil actions experts have to be retained to prove your case. Those expert fees will run in the thousands of dollars. If a doctor's deposition or trial testimony is taken, the doctor will charge by the hour for his time reviewing medical records and testifying. Court reporter fees will be charged to you. These types of fees can really add up and you are responsible for them.
Most of all, be sure you actually do have a good solid case. Get a second opinion if you are in any doubt. As someone else advised, check the reputation and Bar status of the lawyer before you retain him/her also. Lawsuits can be very stressful for all parties involved. It's not as easy as it looks on TV. It's not a "lottery" or "windfall" in a lot of cases. But if you truly feel you have a STRONG case, go for it.