I saw a really cute tutorial for a tiered skirt on the Crap I've Made blog, so I tried it out. I really like how it turned out and the tutorial was really easy to follow.
The only things that I changed were adding ric rac to the topstitching on the first tier and gathering a different way. I hate trying to pull a bobbin thread to gather fabric. It always breaks on me or is too tight in places. I like this method better.
Cut a piece of embroidery floss that's long enough to go the entire length of the fabric you're gathering. Then, using a large zigzag stitch, you sew it onto the fabric about 1/4 of an inch from the edge, being careful to not sew directly on the floss. You want to trap it between the zigzags. The floss fit perfectly into the gap on my machine's zigzag foot, so I didn't have to guide the floss at all.
After sewing the entire length, just pull on the embroidery floss to gather. Once you sew the gathered fabric onto the next tier of the skirt, you can remove the string easily and you're done.
I decided to add a bow.