Contact an organization, such as the Disabled American Veterans, that has individuals who understand the VA system and can advise you on how to proceed. They can also assign someone to represent you at your VA hearings. This is important because your assigned VA center may be far away, and you may not be able to conveniently make your hearings.
File an appeal within 60 days of receiving final notification of your ratings, stating why you disagree with the ratings. If you believe your ratings are too low based on a diagnosis by a physician or other specialist who isn't an employee of the VA, you can submit that person's findings along with your appeal. If the VA agrees to revisit your condition, however, their findings will be based on an evaluation by a VA physician or other specialist.
File a disability claim even if you miss the 60-day appeal period, but be prepared to provide a good reason why you missed it. One reason could be you didn't become aware of the disability until after the 60-day period.
Answer any claim-related correspondence from the VA as quickly as you can. You'll also have 60 days to respond to requests for information, but the sooner you respond, the sooner they can finish the evaluation process.
Make any appointments the VA schedules for you promptly. Failing to make an appointment will most likely result in the VA denying your appeal.