I don’t do much wader fishing, but I spend (what the FW calls) an unhealthy amount of time in waders all fall. Wader belt for sure and PFD if in any sort of current. Even if the water isn’t very deep, when waders fill with water it’s incredibly difficult to do anything, including standing up. If you ever feel in doubt, unbuckle the waders and take them off, it’s worth saving your life. Also use some sort of stick or support pole. I use a canoe paddle, as I always have one in my duck boat.
I had what could have been a very serious accident about 2 years ago in the Mississippi backwaters. I was chasing a cripple in the cattails behind the blind. Ended up needing to cross a very skinny opening in the cattails and didn’t have my paddle. Assuming it couldn’t have been deep being it was only 5′ across and I was in ankle deep water, I went for it. I immediately sank into 7+ FOW. Dropped my gun and instantly unbuckled my waders to take them off. Crawled back onto shallow ground, gained my bearings and went back for the goods. Went diving for the waders, then the gun. Drained the standing water and put them back on. Walked back to the boat to change into dry clothes and we packed up and left…One lesson learned the HARD way.