Always choose a template appropriate to the orientation of your design; it’s best to have text reading ‘upright’ on screen.
If it’s not possible to design the text ‘upright’ (maybe, you need a landscape front and a portrait reverse), then you must ensure the generated artwork’s front and reverse are oriented as you need.
The following examples show how your files need to be supplied, in order for them to print with the correct orientation:

Do not submit one landscape and one portrait side. Instead, rotate the artwork of one of the sides to conform to one of the examples shown here – make it fit a standard template.
Be sure to double check your orientation is correct, especially with Landscape Greeting Cards and Folded Leaflets. When supplied as in the first image, the artwork one page two needs to be supplied upside down.
On Folded Leaflets the Front Panel is indicated by a red border.
As we impose from left-to-right, the message inside will print on the panel opposite to the reverse. Your files when set up correctly should look like these examples:

You can also supply like this:

Or like this:

Your Portrait Greeting Cards will look like this: