to piggyback off of this... (not sure if this is in the thread already)

⌘ + ` to switch between different windows of current application

⌘ + SHIFT + ` to switch between different windows of current application (reverse order)

same for the general application switcher:

⌘ + TAB to switch between different windows of current application

⌘ + SHIFT + TAB to switch between different windows of current application (reverse order)