http://usnews.nbcnews.com/_news/2014/01/14/22303207-husband-of-brain-dead-pregnant-woman-suing-to-remove-life-support?liteYou should not need to hire a lawyer. Ask your doctor or a social worker where you get treatment. Failing that, google the laws of your state on living wills, medical proxies, etc. You will probably find forms you can use. If you don't find what you need, call your state rep and ask for help. Most of all, you need to sign something that shows your intent. Do you want to be kept on life support--meaning breathing, IV nutrition or a stomach tube? Medication? Be as specific as possible.
Mind you, I was fed by IV and a stomach tube for almost two years (but I was not brain dead), and am very happy to be alive today; so I am not opposing all measures. I am just saying that people need to think about these things and write down their wishes--whatever those wishes may be--in a way that has a shot of holding up if it comes to that.