Practice the following techniques as described in the video before painting the feather. You can use one of your blank pieces of paper or the back of one of your previous paintings.
Once you are confident using all three of these techniques you are ready to paint the feather.
As with the previous tutorials paint it twice. Taking time in between paintings to study your work and analyze which techniques you'd like to improve.
NOTE: This is the hardest tutorial of the series. Don't worry if your results don't match the painting in the video, simply by practicing these techniques you are developing transferable skills that will translate into all the paintings you will do moving forward.