All of kat's moves are amazing because most keep her moving. Spend some time in practice mode just moving around. While dashing in the air to the ground allows her to cancel into any move, if you do this and cancel into another mobile move you can really run circles around your opponent and make buttered toast out of your opponents. Combine your speed with your debris attacks and your oppents won't even be able to tell when you attack. A good way to practice this is to do 2v1 using Kat. Get decent at fighting 2 opponents at once and then fighting one-on-one will be a piece of cake.