What colors are you wearing right now? What kind of outfit did you wear yesterday? How often did you wear a hat? Does your footwear change over the course of a day or a week? How often do you wear things you make yourself? Everyone wears clothes, regardless of how much or little thought they put into them, and there are lots of things you could keep track of for a textile data visualization.
Alternately, you could take on a project like Wendy Ward’s Wearing Tally stitches, where she adds a small French knot Embroidery stitch to every garment (or a small label she’s attached to every garment) she owns as she wears it.