After my open water course (where I was firmly cratered on the bottom with 36 lbs of lead), I picked up a dry suit and just started diving with it. However, I was diving with a friend who was an instructor. After diving and teaching for a number of years, I realized what I had missed. I have picked up helpful tips from other instructors to help students develop a feel for their trim depending on the amount of gas put in their wing/bcd versus their dry suit. In the pool, I recommend having students get neutrally buoyant and "transfer" gas from their BCD to their dry suit and vice versa (obviously this means adding to one and dumping from the other) and have them pay attention to if they become head/foot heavy and how easy/hard it is to stay horizontal. This is one tip I received from
@custureri who has a DIR background. I never heard from any WRSTC agencies who do this who didn't have at least some DIR training. So there is more than "just take the class." There are differences in performance requirements in different agencies that you may wish to consider.
As always, proper weighting is paramount: just enough to keep you at your safety stop with an empty wing/bcd and a dry suit as empty to remain comfortable with a nearly empty cylinder, and no more.
The road to diving comfortably with a dry suit is hampered if the dry suit doesn't fit well. I can't emphasize this enough. I taught through a shop that consistently gave my students poorly fitted dry suits, and their ability to overcome that obstacle was seriously impaired. Once they got a properly fitting dry suit, it was magic.
I really don't see the point of PADI's AOW course or other agencies' Adventure Diver, unless you just want the card for dive charters that require it. It is better to get AOW certification by taking full courses, and when you complete the five (PADI) or whatever number another agency requires, you will be better off. Just find instructors who will challenge you beyond minimum standards (without violating standards of course).
I say this as someone who would have done training dramatically different with what I know now. Everyone knows which course I'd take after open water, so I won't say it to avoid the collective groan and request that I shut up with it!