I have no idea where to start. What's the actual first step?

Here is the shortest path that does not waste months: 1. Submit an VA Form 21-0966 today. This locks in your effective date for one year. 2. Log into VA.gov and request your Service Treatment Records (STRs). If you need your full claims file (C-file), submit a FOIA request. 3. List every condition — physical and mental — that started or worsened during service. Do not filter. Let the U.S. Department of Veterans Affairs determine what is ratable. 4. Obtain current medical evidence. A diagnosis strengthens your claim, though the VA may also schedule a C&P exam if needed. 5. File your claim using VA Form 21-526EZ. Submitting all available evidence upfront can help speed up processing. Most veterans leave money on the table not because they got denied, but because they neverclaimed the condition at all.