There are enough articles out there on winter clothing, wearing proper attire, dressing in layers, etc. So I'm not going to cover what's already available. Rather, what happens after you end up in the drink. Either from a spill out of your kayak or maybe loss of balance while wading in a river. However you end up in the water, the situation just became serious, and could become an emergency if not handled properly.
Don't plan on paddling out if you take a good spill. You'll quickly lose the ability to make good decisions, your balance will be jeopardized, basic motor skills will be compromised...simple functions like gripping a paddle may become impossible. Be aware the body shuts down when its cold, wet, and borderline hypothermic. As blood leaves the extremities, your ability to stand or walk will become difficult. This can all happen in minutes.
Lets not make it complicated. The basic need is to get warm and can be accomplished with a change of clothes and the ability to make a fire. I pack a dry bag with a pair of ski bibs, thermal top and bottoms, gloves, hoodie, socks/liner, and jacket. I place those items in first.
Followed by a first aid kit, fire starter/matches, and fire log on top. These are the 1st items I might need. I use a clear dry bag so I can visually inspect everything before I get started. The dry bag goes in the hull of my kayak...and it doesn't come out very often. It's a small pack b/c I keep my trips shorter in the winter for obvious safety reasons.
|A fire is a sure way to improve the situation and get the brain back on task|
This is not an all-inclusive list by any means. There are some other obvious safety tips, like going with a buddy, making a float plan, carrying a cell phone, etc...but these all rely on others helping you. Be prepared to take care of yourself, at least in the beginning. The above is what I feel comfortable with assessing my own skills and paddling locations. You need to make your own assessment and plan accordingly. Be safe.