John, I would suggest you relax a bit. Young people have a habit of doing things that 20 years later will make them shudder and wonder how they survived it. Lord knows, I certainly do. The lucky ones at least get to that point. The trick is to learn from your exprience so you get to the point where you can look back at it. I'm sure you learned what to admit to and what not to, along with other legalities and you won't make that mistake again.
Speaking of learning, the AARP divers on this board and on the boats, can teach you a lot about diving. The trick is to stop, listen and watch. I've taught a bunch of young divers and the hardest thing to teach them is to slow down, relax and think. As you said you were thinking about beer and girls, the time to think about them is during the Surface Interval. When diving you need to slow down, keep your mind on what you are doing and keep aware of your environment.
I would suggest that you find one of these AARP divers and try to learn from them. They will teach you a lot of things, all you have to do is stop, watch and listen. They will teach you the art of diving slow so you can see things, bouyancy and control, as well as hundreds of other skills. The advice they can give you is priceless.
My advice is to get aquainted with a local dive shop or club. Be prepared for some razing, we all went through it, but its almost always good natured. They will teach you by example how to become a good diver and to really enjoy the sport.
You can eventually figure it out on your own, but you will end up learning a bunch of bad habits in the process. And may even get hurt. No one wants you to become another thread in this forum.
I was on a boat with a diver that had just done something like his 2000th dive. He told me that at 20 dives he thought he had it all figured out, at 100 dives he realized he was just starting to learn. The issue is at about 20 dives a bunch of things click, and it makes you a bit cocky, that's when things go wrong usually. When I hit a 100 dives it dawned on me that while I was a good diver, there was a lot more I needed to learn, and it wasn't something I was going to get in a class, the only place I was going to get it was from the more experienced divers and with more experiences of my own in a controlled manner.
It would have been much harder if I didn't have a good group of diving friends with more experience to teach me.