Hey there, not a professional artist but figured I might have something useful to add! It's great that you're using the full range of values here, not afraid to go dark. That's something I have to work on. If I had any advice, it would be to have your mid-dark tones be a bit darker, and to try your best not to draw with 'chicken scratch' lines. Many of your lines are great and confident! But there are a couple spots, most notably on the shade of the stem, where I can see you weren't sure about where to put that edge. Overall though I can see you've attacked this exercise in a very focused way. Keep it up!