Another favorite tool in my pencil case is General's Sketch & Wash Pencil. It's water-soluble graphite. I enjoy it, as up to this point in time, I don't have the patience to create shaded pencil studies. I do love working in black and white. You can concentrate on tones versus color and in the end, these studies will help you work with color.
I drool when I look at the drawings of Debby Cotter Kaspari. They make my artist soul want to push the comfort envelope and give the 'pencil' another try. We'll see what this year brings :)
For now, though, I want to make sure you try your hand at the sketch & wash pencil. They come in a 2 pack which includes a metal pencil sharpener. This pencil will also add another shade of black to your watercolor pencils. Sometimes black is just too black and the tone of the graphite does the trick.Both the storm studies above and the trees to the left were done on watercolor paper.
The sketches of the egret were done in my AquaBee Super Delux sketch book. A fun exercise is to draw just the shaded areas of your subject. This was my quest while observing this Great Egret hunting.