Hey so I used this method for my last submission and I thought it might help some people out. Previously I had been using strange margins and bleeds that in retrospect I don't think look very good. This method makes it a lot cleaner.

The only important aspect here is setting up your guides. With correct guides in place it'll make it a lot easier to place all of your content.

First I like using millimeters, so if you want to do that (and it isn't that way by default) click on Document Setup and then change your units.

Next make sure all your guides are visible by checking View > Show Guides and View > Show Column Guides.

Now click on View > Guides Manager

Now add your column guides. Set 4 columns and 2 rows to have your 8 mini pages. Now you have to decide margins. I selected 6 mm margins because I found that's about as close to the edge of the page I can get on my printer. Set all your margins to this value and set the Gutter for your column guides to twice this value.

Your page should now look like this:

Now you need guides for where to put your creases. In the Horizontal Guides section click on the little page button that says "Add new horizontal guide" when you hover. This should add a new guide in the middle of your page horizontally.

Now do the same for vertical.

You still need guides for the other two vertical creases. Add another vertical guide and it will appear in the same place. Click within the text box and add a "/2".

Press Enter and it should automatically divide the number by 2.

Now just one left. Create another guide (it should be at 139.7 again. Or whatever your center is). Click within the text box again and add a "+69.8" or whatever your smaller value is.

Press enter again and you should have all of your guides.

The page should now look like this:

Now you're all set! These guides will make it easy to place lines for your creases and make sure all your pages have the exact same margins.