You should read The Elements of Content Strategy by Erin Kissane. It's from A Book Apart. As for shorter display copy, starting with a simple, clean writing sty

You should read The Elements of Content Strategy by Erin Kissane. It's from A Book Apart. As for shorter display copy, starting with a simple, clean writing style is a great start. From there, validate the assumptions you make with your initial copy. You can use tools like Kissmetrics or Optimizely to test how successful different approaches are.