Note I've been using the Westalee ruler foot and not the freemotion foot that comes with my sewing machine.
Trying the set of 4 feathers rulers ranging from 2" to 5".
While you could just pick up these rulers and use them I found watching (and sometimes rewatching) the Westalee video sped up the learning process quite a bit.
No marking of the individual feathers is required however having a basting line or marking straight lines on either side of the feathers helps to keep the feathers uniform and straight.
Straight line of feathers using one sized ruler.
Wavy line with different sized feathers using a combination of rulers
Attempting curved cross-hatching using the Westalee straight and curved ruler.
I'm getting used to the edge of the ruler not being where the stitching line will be but 1/4" in from that. This catches me out when I'm getting to the end of a shape and need to line the ruler up - it is too easy to line the edge of the ruler up with the point, start sewing then realise you're not going to end in the right place!
Still working on getting the stitch length even and better start/stops ...