My Drwaing Trial

I got a book named "Lifelike drawing in colored pencil with Lee Hammond" from the library. When I saw the drawing in that book I was impressed very much. But I was worrying how I am going to draw the trees. Somewhat I managed to draw the plants in front of the house similar to the book, but trees as usual not came out well as it is in the book. Still trying to draw trees.

I find difficult to draw the plants and trees, they didn't come out as I expected. Still learning to draw plants and trees. I think this drawing will be more perfect if I would have used color pencil instead of oil pastels.