1. Get a military defense lawyer. The first thing you should do is get a lawyer. Why? Because a lawyer can get involved right away, help gather evidence, and give you advice to keep you out of trouble. If you ignore the rest of this post, follow this piece of personal advice. Many of my clients have regretted not getting a lawyer right away.
2. Don't talk to ANYONE other than your lawyer. This means law enforcement. If the police or special investigators want to talk to you, rest assured it is NOT to get your side of the story. It is to try to get information they can use against you. For example, if you tell them you went to a party the weekend before the test, they will try to prove that you weren't there.
In addition, don't talk to your friends and family about this. Even though you might have a good reason for the positive drug test, don't tell anyone. The reason you think may not be the reason you tested positive. Any statements you make regarding your drug test will be taken out of context and framed in a way to make you look guilty.
3. DO NOT POST ANYTHING ON Facebook, Twitter, Reddit, or any social media. Any statements you make, in person or on line, can be used against you.
4. Write down everything that happened to you before you took the drug test. Mark this piece of paper "For My Attorney" because it will be what you give your lawyer. Memories fade quickly. While the events are still fresh in your mind, write down where you were, who you were with, and so on. Try to be as specific as possible. Don't write, "I went to a bar." Write "I went to Smith's Pub and drank around 2-3 shots of vodka." Keep this paper in a secure place and don't show anyone.
5. Don't believe what you read on the internet. First off, don't research any of these issues on you your work computer or home computer if you live in the dorms. This may leave a trail of computer forensic evidence that will haunt you later. I won't tell you not to do any research, because it is only human. But be careful what you read. The internet will give you lots of explanations for a positive drug test, most of which are not true. For example, second-hand smoke is unlikely to make you test positive. Unless the poster is a forensic toxicologist, they probably don't know what they're talking about.
6. Keep a positive attitude. If you are innocent, then give the system a chance to prove that. If you aren't, it's not the end of the world (even though it feels like it). A positive drug test is not the end of your life. Pray, meditate, go for a run or do whatever you need to do to balance yourself.
7. Be a good troop. While you will be eaten up inside, keep going to work and do a good job. Talk to your attorney about seeing a private, off-base counselor if the pressure is too much. If this incident is alcohol related, consider attending Alcoholic's Anonymous meetings. They are free, anonymous, and may help later on.
If you have any questions, feel free to call me at (303) 578-0595. I have guided many clients through this process. A successful defense begins with making smart choices right away. While every case is different and past results do not guarantee results in your case, I have successfully defended many clients who tested positive for drugs.