The low brace is a ‘bread and butter’ (i.e. essential!) stroke that everyone should know and practice. The low brace will prevent a capsize in most situations and can be used in a K1 or sea kayak (or any kind of kayak for that matter) and should become an automatic response to losing your balance.
To perform a low brace when off balance, push down on the water with the back (non-drive) side of the blade (no need to slap the water as is sometimes taught). Elbows are above the hands and knuckles facing downwards for a powerful stroke. Your upper hand (the one out of the water) should be low down to keep the paddle shaft as horizontal as possible
Try to keep your body upright, over the centre of the kayak at the start of the stroke. A refinement is to push the paddle forward slightly as you push down which will help. Your head should move down towards the blade on the water as you start coming up. This will help to rotate the boat under you.
The video here shows the movement: https://www.youtube.com/watch?v=CIk9TvD9d4Q
Sometimes you can anticipate the need for a low brace, for example if a wave or boat wash is coming your way (particularly from the side). Always brace into the wave as it’s just about to hit your kayak.
In a K1 you can also perform a relaxed version of the brace to maintain stability if you need to stop paddling or look behind you for example. Simply place the back of the blade on the water slightly behind your hips – no need to push down hard. If you need to look behind to see where your mates are (or an approaching rowing boat), look behind on the same side as the blade on the water.
Practice on both sides.