Professional florists make pew bows with ribbon that have 25 yards or more on the bolt. It may seem like a bargain to buy ribbon at discount stores (like Wal-Mart) - but you begin to realize that there is barely enough ribbon on one bolt to make more than one or two good sized bows. You have to go back again and again to buy more ribbon.
I like using sheer organza because it's stiff enough to make a crisp bow that holds good shape to the bow loops.
I make my bows the same way whether using satin or sheer ribbon. It's important to twist the ribbon tightly after each loop and pinch it tightly between two fingers.