There are lots of 'tricks' touted as to how to survive hypothermia. Getting dry, warmed externally, insulated and taking on fuel are all good. I'm not convinced that 1 approach is noticably better than another in reality

But priority number 1 is before you hit the water - PRACTICE! You need a simple foolproof plan that you have drilled if you have a hope of self-rescuing. Do not expect to be able to think it through or do anything the tiniest bit fiddly when the moment comes

Kit needs to be within reach, unpack quickly, not leave you scrabbling for kit etc