I like to trace the reverse of the pattern on light weight fusible web, and then fuse it to the wrong side of the fabric that I want my leaf to be. Next I cut out the shape on the pattern line and fuse it to my quilt. Once you stabilize the piece, (I like a medium weight tear-away stabilizer), then you can thread paint the veins and do any shading you desire.
Don't forget to try different types of threads, like the variegated thread on the yellow leaves, or the metallic thread on the bottom leaf.
Of course if you don't have a camera, you can get similar results using the low tech method of doing a leaf rubbing using paper and crayons! Hoping to inspire you to a fall project, Linda B.