NovaChoosing a position
Bottom-center and bottom-right are the most conventional placements and the safest choice for anything formal — a report, a contract, an academic document. Bottom-right in particular avoids colliding with a document's existing footer text in most templates.
A grid-based position picker, rather than typed coordinates, makes this easy to get right without guessing — clicking a corner or edge and seeing exactly where the number lands on the actual page before committing avoids the common mistake of a number overlapping existing footer content.
Picking a number format
Plain numbers ("1", "2", "3"...) are the most common and least visually intrusive choice. "Page 1 of 12"-style formats are useful for printed handouts where a reader benefits from knowing the total page count at a glance — particularly for something that might be read out of order, like a stapled packet.
Starting from a number other than one, or numbering part of a document
If the file being numbered is one chapter or section of a larger document, starting the count from something other than 1 (say, 45) keeps the numbering consistent with the rest of the set once everything is eventually combined.
Setting a page range limits numbering to only part of the document — useful for skipping a cover page or table of contents that traditionally is not numbered, while still numbering the body pages that follow.