My three are regular little fish......a reusable swim nappy and an all in one rash suit for them all......

In terms of what to do, (and Shar will be able to add to this in more detail, I am sure!)

~ Songs that get them used to moving around in the water
~ Monkeying around the side of the pool edge (to help build their upper body strength to ultimately enable them to pull themselves out of the water, as well as for them to gain the understanding that the pool edge is the safe spot, IYKWIM?)
~ Songs that give them the idea of kicking in the water
~ Blowing bubbles at the water level
~ Getting their hair and face wet & wiping the water away from their faces

(My 3 have been in lessons for ages......I could run the class I know it so well, LOL!)

At 12 months, I think it is all about building confidence?