Action buttons should come at the top of pages as much as possible.
The action button is a styled link to make it stand out.
Don't force the user to scroll down to perform the task. Supporting or introductory information should come after the action buttons or can form part of the process upon clicking the action button - for example the first page of the form includes details on filling out the form.
If a page contains a key action - consider setting the page as a promoted page in that section so it appears in the navigation structure.