[bthoven]

Now I'm very happy with the following format:

size 9.5x11.4cm
margin: left/right/top = 0.1cm, bottom= 0 cm
font: FreesiaUPC size 10 bold (or size 12, if not bold)
On OpenOffice:
Line Space = 0.45cm (default = 0.5cm) in order to accommodate more lines per PDF page, and is still easy to your eyes, well at least for mine 8-).
On MS Word: use line spacing fixed to 13 points

I also attach 3 documents for future reference: each one has different line spacing: 0.5cm, 0.45cm, and 0.4cm

Though 0.4cm is still readable, it's a bit too "crowded"; 0.45cm spacing seems to be a good compromise.