Here's a link to Social Security's eligiblity process http://www.ssa.gov/disability/step4and5.htm
Here's their home page for disability http://www.ssa.gov/disability/index.htm
You can do an appeal at this link https://s044a90.ssa.gov/apps6z/i3441/ee001gen.jsp
The Best way to improve your chances is to obtain a lawyer. Nine times out of 10 you will be denied on the initial claim. With an attorney you chances increase a lot because they know the law pertaining to SSDI and SSI. Try one of these Social Security Disability Lawyers out:
Social Security Disability Denial Attorneys!