I'll be the first to admit, I'm not good at sewing. In fact I'm downright awkward with a needle and thread, however even I could attach some simple buttons and flowers to a headband so if I can do it, you can do it.
The first one I took ribbon and made a bow by twisting the ends in a star like pattern.
I then sew three buttons to the center of that bow.
Here is one example of how I cluster the buttons and flowers together.
And here is another example of how I spread them out along the headband.
And here is my little model showing off her new headband.