Recently I had to find certain parts of my medical records from the time that I was in the service and found that there was a lot of information available, but in bits and pieces. Most of the people that I spoke to knew only small parts of where to go and how to acquire the records. The fact that I kept getting sent to various offices and running into a variety of people, some who wanted to help but had no idea where to go, and many more who didn't care and left me at dead ends is what prompts me to write this. The process is different depending on the status of the veteran, if they didn't file a claim with Veterans Affairs, if they did file a claim with Veterans Affairs, and if they are deceased.
The first advice I'd have is for anyone who is still active duty and has access to your records, make sure you photocopy the records before you get out. This is especially true for anyone who plans to pursue an education as many schools and universities require a copy of your immunizations.
For anyone who did not submit disability paperwork, I would first trying going to the eBenefits website. If you're lucky they may have actually scanned your records in, if so then you can request parts of your personnel and medical files and get them in a very quick period of time. If the records aren't scanned in, well they at least e-mailed me back within a couple of hours. Don't be surprised if your records aren't there, I know people that have been waiting over a decade for access to their records online.