Personally, (still being a newbie myself) I would do a pinwheel bow. When I asked everyone on this forum what is the easiest bow to start with, the answer was pretty unanimous. You can find a tute here: Free Pinwheel Hair Bow Instructions: hairbow free directions, hair bow business work at home
They actually do it by eyeballing it, I use a piece of cardboard so my loops are the same size. Just figure out how wide you want your bow, cut out a scrap piece of cardboard (even a cereal box or something similar) and use that for your template to wrap the ribbon around however many times for the amount of loops you want. HTH!!