I have had several requests to do a demonstration based on trees, and so hopefully the following will help.
Today I am using 1b140 NOT paper.
However, I recommend that you try as many different kinds of paper as possible. The main three groups are Rough - a textured surface. Hot Press - a very smooth surface, and NOT which means 'Not hot pressed' and is somewhere in the middle.
The indicated weight of the paper, i.e. 140 pound simply means that the ream of paper (500 sheets) weighs 140 pounds.
I have been using this same pallette for many years. Don't wash your pallette clean after use. Just run it under the tap, and with a brush clear of the 'muck' and just leave the blobs of clean colour. This paint is activated by adding water, and is good until you have completely used it up.
You can spend a small fortune on sable brushes, but I am very happy using synthetics which are getting better all the time.
I am using tube paints. A mix of Winsor & Newton Artists grade and Winsort & Newton Cotman student grade. The tube paints are much 'juicier' allowing me to make stronger marks.

First marks - on white paper.
Mixing burnt sienna and prussian blue I apply strong juicy paint to the shadow side of the tree trunk. With a wet brush, which still has a residue of paint on it, I indicate the light side of the trunk. Remember whenever you are painting from life, or otherwise, always consider your light source.

Whilst the paint is wet on the paper, I take a knife and scrape out the beginnings of branches.

Taking the side of my knife I scrape along the trunk to give the illusion of aged bark.
Using a 'rigger brush' which has extremely long bristles I begin to indicate branches. Rigger brushes were first designed to paint the rigging on sailing ships, hence the name.

Using a mix of burnt sienna/prussian blue for the darks, and Winsor & Newton Gold Green for the lights I begin to add the leaves. Observe trees in nature, to see how they are made up of many shades of greens. When we are walking through a park we don't see all the leaves....we see the bigger picture.

Adding more leaves, and continuing to use the knife to scrape out wet areas within the branches and leaves, and grasses at the base of the trunk, a sense of energy is achieved. I have also indicated some trees in the background to the left of the trunk, and brought some cadmium orange into the image.

The finished image. Note I have left some white paper which gives an overall sparkle to the image.
For this demo I am working off an orange ground. When doing this make sure that the ground is completely dry...i.e. at least 24 hours dry.
First marks.
With the burnt sienna/prussian blue mix I apply rich juicy pigment to the shadow side of the trunk. Working very quickly into wet paint, I use my knife to scrape out, giving the illusion of energy and branches.

Because I am working off a 'ground' I now mix Winsor & Newton Gouache permanent white with the gold green transparent water colour to indicate the lightest areas of the image.

You will note that using the side of the knife I scraped out the bark, and pulled up grasses in the foreground.

The finished image.
Leaves have been indicated in a very free form manner, and I have moved colour around the image bringing balance to the whole.
Note that I have added Winsor violet and cadmium orange to the mix.

I do receive many emails from people asking about these demonstrations. I will get back to everyone, although it might take a few days.
Most importantly, remember to WARM UP and PLAY with your paints. You are better off playing for fifteen minutes a day, than painting for five hours every two to three weeks.
When you are warming up/playing use newspaper or inexpensive wallpaper lining. This will free you up.
Have fun.
A Bientot
Miza-T

A different use of watercolours,I like it.
xx