First draw a leaf pattern on stabilizer, you can freehand or trace a real leaf. Sandwich this with batting (scraps can be used) and one leafy fabric. I use glue sticks to assemble this sandwich.
Next stitch around each leaf, this is just so you can see your traced lines after you add the next layer.
Go ahead and glue on another layer of your leaf fabric to the stabilizer. Stitch around your previous outline and add veining at this time.
At this point you should have a quilt sandwich that has fabric, batting, stabilizer, fabric and all the leaves outlined with stitches and veins. You can now cut these out.
If you want to add a picture as I did, rough cut it out and glue to one side of the leaf, then trim, leaving as much next to the edge of the leaf as possible.
You will then sew a couple of rounds of close zigzag or satin stitch along the edge. I have found that if I do one round then another it has better coverage of the edge.
Tip: if there is still white batting showing thru to the edges, get your colored sharpies out and fill in; nobody will ever know the difference!
Have fun make a bunch and let me know if you come up with any other tips.