Thank you so much!!
I have chalk painted over 100 pieces of furniture and kitchen cabinets. With few exceptions, I always apply a couple of coats of Minwax Polycrylic (or any good brand) in a matte finish instead of wax. For a nice durable finish, sand lightly between coats. If you use wax, you will have to rewax periodically because, just like any wax, it will wear away and dry out over time. But I like the look of waxed furniture so sometimes I apply a thin coat of wax on top of the dry poly for a "softer" look. Good luck!