OK, so now you know what shape your mini will be, and what will go in it, either a collection of finished work or all new work. Now you need to decide HOW MUCH work you’ll put in there.
If you are using the DIGEST format, meaning paper folded once, no matter what size it is, you will have to fill pages in muliples of four, since each sheet of paper folded in half has four pages.
If you are using the MINICOMIC format, you will have pages in multiples of eight.
If you are using the MICRO format, you will have pages in multiples of 16.
Make a list of what you want to put in your comic, and count them to make sure you have the right number. Add and subtract pages until it comes out right. Make sure you are adding a front cover (FC), back cover (BC), inside front cover (IFC), and inside back cover (IBC) into your page count.
Make sure you are planning to print an indicia of some kind. An indicia is the basic legal and personal information you want to have in your book. At the minimum, you want your email address and a copyright notice of some kind. You might also have your street address, information about your stories, thank yous, whatever. This information is commonly found on the IFC or BC.
Keep in mind contents pages, empty pages, title pages, ads, or anything else you might want to add.
Now look at your list and think about order. Remember some basics about the reading experience: in the Western tradition, people expect to start new stories on a right-hand page (also known as “recto”), which are always odd-numbered, and end them on a left hand page (AKA “verso”), which are always even-numbered. If you can respect that tradition, your readers will thank you. (Obviously, that expectation is reversed in Asian tradition, and in any culture where books are read by opening the left edge of the book.)
Work out the final order of stories (it will probably take a few tries of re-ordering them), and you’re ready to go.