Hi Mike. You don't HAVE to get a lawyer but they do help A LOT. What mine told me is that the government will do anything to not have to dish out money no matter what. He said that bringing a lawyer actually scares them into getting things rolling because they don't like having to deal with lawyers at all. For me, it cost about the total of one check from SSI to pay off my lawyer (~$850). For me it was worth the cost because I would have lost it otherwise. I was a student in college at the time and really didn't want to deal with the hassle.
These are the steps you need to take to get started if you choose to do this without a lawyer:
Step 1: Review the Adult Disability Starter Kit. This kit answers common questions about applying for benefits and includes a worksheet that will help you gather the information you need.
http://www.ssa.gov/disability/disability_starter_kits_adult_factsheet.htm#disability
Step 2: Fill out the online Adult Disability Report. At the end of the report, we will ask you to sign a form that gives your doctor permission to send us information about your disability. We need this information so we can make a decision on your claim.
https://secure.ssa.gov/apps6z/radr/radr-fe
Step 3: Complete your application for SSI disability benefits by calling our toll free number (1-800-772-1213) between 7 a.m. and 7 p.m. Monday through Friday and making an appointment. You may choose to apply for benefits either by phone or in person at your local Social Security office. One of our representatives will help you apply for the benefits. Please have your Social Security number handy when you call us. If you are deaf or hard of hearing, you may call our TTY number, 1-800-325-0778 during the same hours.
It's best to make an appointment over the phone rather than just walking in and waiting for a representative. My mom did all of this for me when I was a kid without a lawyer. She doesn't remember all of the details though. But above is what Social Security says to do. All of that info is from:
http://www.socialsecurity.gov/
*EDIT: THIS IS IMPORTANT! When filling out any information about your disease, only talk about your worst days possible. NEVER say that you feel fine here and there. This helps the decision to go in your favor. This is what my mom told me to do when I applied for my appeal and I bet that's what she did when she applied for me. Don't forget this.*