In Drupal Commerce, what Rules need to be set to go directly to checkout after Add to Cart button is clicked? On a fresh drupal commerce install, clicking on add to cart brings your back to the same page. What is needed in Rules to have it go straight to checkout after clicking on the Add to Cart button?
Since this isn't built into Drupal commerce itself, you have to create a new custom rule (admin/config/workflow/rules). The event would be called:

After adding a product to the cart

and then the action would be:

System > Redirect Page

URL should be: checkout