I installed the dashboard using the Helm chart, which provides convenient configuration options for a local cluster like skipping login and whether or not the service account created for dashboard gets broad cluster admin privileges:
$ helm install stable/kubernetes-dashboard --name dashboard \
--set=enableSkipLogin=true,rbac.clusterAdminRole=true
Disclaimer: these settings are obviously a bad idea for a non-local installation!
The installation outputs steps at the end for enabling a port forward just as @kevinpz showed above, and again as Kevin described an Ingress Controller can be set up for a more semi-permanent means of accessing the UI.
Installing Helm should be as simple as this if you don’t have it already, assuming you have Homebrew:
$ brew install kubernetes-helm
$ helm init --history-max 200