Best practices are, odd numbered pages should appear on the righthand side (recto) of an open book, and even pages should appear on the lefthand side (verso) of an open book.
Your interior file should include interior pages only--not the outside or inside of the cover. (Your cover should be its own file, separate from your interior file.) Your interior file should start on page i or 1, on the righthand side.
Bookmobile needs an even page count, so if your interior file ends on page 77, for example, we will add a blank page for 78.