Make buttonholes that look authentic by sewing two rows of zigzag stitching very close together. When selecting trims for small doll clothes, make sure their size is proportionate to the garment. A trim suitable for adult clothing would be much too large for doll clothes. Try using invisible thread when stitching on trims. Or attach trims with glue.
Regular buttons are much too large.
Try hand-stitching pearls or beads instead.