Create a cluster in local minikube, and/or set up k3s. Deploy an application and get comfortable with how to write and structure resource files. Deploy an Ingress controller from scratch (such as ingress-nginx), installing/managing Helm application charts; I found it mostly trial-and-error but learning concepts will come naturally once you need to implement them. Read lots of docs, and keep in mind various things change between Kubernetes versions. It's not magic or particularly difficult, just a few concepts + YAML files on top.