Draw a small spiral or oval for the center
Add a few curved petals around the center
Layer larger petals outward in overlapping curves
Vary petal sizes and shapes for a natural look
Add more petals around the outer edge
Draw the stem with two parallel lines
Add thorns along the stem if desired
Sketch two pointed leaves on each side of the stem
Add leaf veins with simple lines
Darken the final outlines
Erase extra sketch lines
Shade the petals and leaves for depth