A leaf looks like the easy thing to draw until you try it. The outline goes fine, then the shading turns into a flat grey shape with some lines on it. This walkthrough fixes that by treating the leaf the way a botanical illustrator does: work out what kind of leaf it is, build the structure, and let the shading carry the weight at the end.
It follows Vlada Repina Art on YouTube, filmed straight down over the page with a real hydrangea leaf sitting beside the paper the whole time. One graphite pencil does most of the work. Sixteen minutes of video, closer to an hour of drawing if you take your time over the small veins.
What you need
Two or three graphite pencils covering hard through soft, an ordinary eraser, a kneaded eraser and a pad of drawing paper. A sharpener matters more than it sounds, because the fine vein network falls apart under a blunt point. And a real leaf. Pick one off a plant on the way in rather than working from a photo, since you need to tilt it against the light.
Why this one reads as real
Three things carry it. Each vein gets a second line beside it so it has thickness instead of being a scratch. Every segment between the veins is shaded dark along the bottom and light at the top, which turns a flat panel into a shallow dip. And at the end one half of the leaf takes a single pass of extra tone, so the whole thing curves away from you.
Where it goes wrong
The outline is too dark to hide. The oval is scaffolding. Draw it at a pressure you can lift back out with a kneaded eraser, because the notched edge replaces it.
The shading turns into grey fog. Tone needs a direction. Heavier under each vein, lighter toward the top of the segment, every segment the same way round.
It goes muddy at the end. Stop earlier than feels right. Paper showing through the graphite is what makes it look like a leaf.
More botanical drawing
The same structure-then-shade method runs through a rose and flowers, and a stack of these leaves is most of the work in a tree. For the fundamentals underneath all of them, start with how to draw.