Start with a bean shape
Draw another bean-like shape for a petal
Draw another petal overlapping the first
Another overlapping petal
Can you see the rose start to form? Continue putting petals on overlapping each other as if they are spiraling outward as you draw. They should get bigger as you go.
Once you have the shape, you can add color or a stem or leaves, whatever you feel necessary.
For leaves, draw a leaf shape with a line through it.
And veins in the leaves
For color I like to start with yellow where the light hits
For the petals I like to use a pink for the yellow fading to red
Use dark purple for shadows on the petals
Use dark green for the shadows on the leaves
Finish it off with red and green and then your done.