and welcome to IRV2. I too am a newbie and am on the RV learning curve haha.
My one mistake so far DID have to do with the black tank ;-/ I was empting it out and didn't make sure the hose was connected all the way, and plop! It fell off and black mattered decided it was going to get everywhere. I quickly closed it and didn't have too big of a mess on my hands but it was still disgusting and taught me really quick to make sure everything is on correctly and wont pop off haha.
Other than that triple check all your inside doors / cabinets / luggage etc, because stuff likes to open up and make messes / break. I would check the fridge and pantry doors more than once for sure.
Happy travels and good luck with your Florida trip