Finally! A chance to break out my Eagle Scout knowledge for real. I don't have any experience sleeping in abandonments specifically, but I do have some wilderness and generic camping experience, seeing as you sound like the type of guy who's done a bit of generic camping I'll skip to the rules for more dangerous places.
Beyond the basic Ideas like packing lights, maps, lots of water, etc, make sure you have some bear spray. There are a lot of animals that could sneak up on you and ruin your evening, wild dogs, and in Michigan it's reasonable some actual bears. Barring a hefty supply of water in your vehicle, Bring purification tablets and a filtration system, in case you do get lost, they're almost weightless and could literally save your life.
Fires. Learn to make them, learn to be safe around them,learn how to clean up after it's gone, always build a rock ring; never leave a fire open, and NEVER leave a fire unattended. Also burn bundles of sage to keep mosquitoes away. Works wonders and cheaper than repellent, you can find it naturally pretty much everywhere but unless you have experience I don't recommend trying. Also keep a big bucket of emergency water ear it at all times.
Use tents, it may be tempting to sleep under the stars, but you'll wake up the next day with half your face numb from bug bites and it's not a fun time. Avoid sleeping inside any buildings, unless you know for certain the air is safe for an overnight stay, a respiratory infection will ruin the trip and your next month. Buildings can usually be used for cover from the storms, but if it looks like I could collapse best to just get in your car and sleep there.
Entertainment! Every camp needs it, electronics not allowed! Playing cards are great,endless games with those, also bring a ball, just for fun.
Carry cash, lots of cash. Never know when some Podunk gas station never updated to card readers, or the internet will be down and it's cash only for the day.
Misc items people forget: Duct tape, candy for road snacks, rope, big knife (6" blade is my personal favorite), Separate backpacks for hiking and walking around. First Aid kit with Gauze; Moleskin; antiseptic; bandaids; scissors; all the normal drugs plus a generous supply of itch cream; Cold compress; sheet of paper with emergency numbers on it; and a little booklet that tells you what to do (best to practice beforehand), Next a journal and pen, and some ziplock bags to waterproof stuff.
Those are most of my tips, but I'm happy to answer any questions! as sort of a P.S. the BSA handbook is available pretty cheap and has a really great mix of first aid, tent pitching, firebuilding, and general outdoor instructions that a lot of other books are too specific to have all of together. It's great for a beginner or a quick reference for someone who just needs a refresher. Plus diagrams designed so that kids can read them never hurt.
Happy trails!