Once you're sure you have adequate exposure wear, then the next thing you should cover (IMHO) is possible regulator freeze-up at depth. For recreational dives in the Great Lakes Michigan, Superior, and Huron, I recommend a Y-valve or H-valve with two complete, environmentally-sealed regulators, on a single cylinder that is larger (perhaps) than you normally dive. (So, an HP100 or a LP108, maybe.) Connect one first stage to your BC, and the other to your drysuit.
Practice 2nd stage switches and 1st stage shut-downs while diving.
Practice disconnecting/reconnecting your BC inflator hose and your drysuit inflator hose while diving.
Practice orally inflating your BC while diving. (Many of us haven't done this since our open water check-out!)
Practice breathing from your regulator when you don't have a mask on and the water is very cold.
Practice the above skills using the gloves/mitts you intend to wear on your Great Lakes dives.
The above recommendations can be acquired (gear) and practiced (skills) where you are now, so that you'll be more prepared for your Great Lakes dives.
rx7diver
P.S. One other thing: Make sure your drysuit underwear is adequate. It needs to keep you reasonably warm at depth (so, it should NOT compress too much) and if your suit floods (so, cotton long underwear is NOT recommended, e.g.).