Welcome, and above all else, thank you for your 12 years of service, it is immensely appreciated by all of us who get to enjoy the freedoms that you fight for.
As for advice... Well, I myself am a noob, as I've only been collecting/investing for a little over a year now, but for what it's worth, here it goes:
1. Read up on the many articles posted on this site. There's a little bit of everything, ranging from where to sell (e.***. ebay vs. amazon), what themes are likely to be profitable, how to manage/organize your Legos, etc.
2. Familiarize yourself with Legos in general, so you know what's popular and what's not, and you can recognize a good deal when you see one.
3. Use common sense and healthy skepticism when seeing listings online (such as on craigslist) that seem too good to be true.
4. If you're going to buy any used sets and/or bulk, unsorted Legos, make sure you understand what you're getting yourself into. Many sets will be incomplete, dirty, and a pain to go through. If you don't enjoy spending hours sorting, building, and taking apart these sets, it may not be worth your time. If that's the case, invest in NISB (New In Sealed Box) sets instead.
5. Don't take anyone's advice, no matter how experienced they may seem, as the ultimate truth. We're all human, we make mistakes, and ultimately, investing is a gamble.
6. Remember that this hobby/investment can take a lot of time (and space) that you might want to use for something else. In other words, don't get yourself in too deep unless you really enjoy this!
7. Include your family as much as you can (and as much as they'd like to be involved). If you're married, your wife may be a great partner. Even if she isn't interested in Legos right now, be transparent with her to avoid going the way of many of our fellow Brickpickers (I won't mention names) who receive shipments at a different address or try to sneak in boxes when their wives aren't looking. Seriously, just avoid the headache: as much as I love Legos, they aren't worth it! And of course, as your kids become developmentally ready, they will likely love "helping" (probably more like getting in the way, but hey, Legos are TOYS after all)!
(Can you tell I'm studying to become a psychologist?) =)
Obviously, these are just a few key points I thought off the top of my head right now, so for more info, go back to my #1 point. Good luck!