When I colour leaves of trees and flowers, I always use several coloured pencils to build a colour with depth and variety.
I normally start with a light colour and start layering with darker colours. Because I do the layering very gently, I can put lighter colours on top of darker ones.
Here are two videos where you can see how I colour a leaf with different pencils.
I start with yellow and colour the first layer very gently.
Then I add Olive Green to some areas of the leaf.
The next pencil is a brownish green pencil.
After these three layers of colour I take Sap Green to give the leaf a green colour.
I end the process by highlighting certain areas with Yellow and Light Green.
I finally use a brown pencil for shading.
When I continue this drawing I will add more shading to this leaf.
The colouring page in these videos are from Johanna Basford's colouring book Secret Garden.
It is the most beautiful colouring book I know!
If you want to purchase Johanna Basford's wonderful colouring book, you can use one of the affiliate links below: