A good way to practice kicking for breaststroke is to isolate the kick on its own, and to include the breathing as part of the component in practicing the kick. This will help you with the rhythm of the breaststroke, and also allow you to practice your breathing on top of your kick. There are a couple of ways you can go about practicing the kick. On your belly, you can push off in a streamlined position, then break out your arms into shoulder width position, and then just do a repetition of four kicks. One, two, three, four, with your face in the water, and then after you do your four kicks, take a quick breath, bring your face back in, and then repeat the four kicks again.
The second drill for the breaststroke could be with your arms at your sides. You push off in a streamlined position, pull your arms down to your hips, and then kick four times before taking a breath. This drill in particular is good, because it allows you to bring your calf muscles to your fingers and give you the right type of propulsion for the breaststroke. So you would kick four times with your arms down. One, two, three, four, take a quick breath, and repeat the four kicks again. These are some of the drills that you can do for the breaststroke kick.