Pen and ink set
Trees and foliage are a great subject for drawings because they are found nearly everywhere, and they're not difficult to reproduce. Drawing trees with a pen and ink set is not so different from using a more usual medium like pencils. The most important thing to keep in mind is that everything you put on the page is permanent. Draw patiently, and slowly.
Instructions
1. Draw the basic structure of your tree and foliage with a pencil. Do this lightly, so that it can be erased later. It is important to have a basic map of what you'll be drawing before you begin with the pen and ink, because the pen and ink is permanent.
Draw the trunk of the tree with two parallel vertical lines that curve inward toward the middle, and then curve back outward toward the portion of the tree that the leaves begin. To draw the foliage of the tree on top of the trunk, draw a wavering line around the perimeter of the foliage.
2. Choose a fine-point pen nib (or even a crow quill pen). Assemble the pen shaft and the nib, then dip the nib in the ink. Test the nib on a piece of scratch paper before applying it to your drawing.
3. Outline the exterior of the trunk, following the lines you drew in Step 1. Connect the two sides of the trunk at the bottom with a line in the middle that looks like a shallow, upside down V. Connect the two sides of the trunk at the top with a line that looks like a shallow V. You have just drawn the trunk, roots and bottom branches of the tree.
4. Use your pen to shade the inside of the trunk. Shading may be done by drawing lines that run parallel to each other inside the trunk. These lines may be diagonal, horizontal, or vertical. To shade one side of the trunk more heavily than the other, draw lines that cross over your first lines, over one half of the trunk.
5. Outline the foliage around the top of the tree.
6. Draw a series of wavering lines throughout the interior of the foliage. These lines may be drawn in a series of stripes across the foliage for an interesting pattern, or they may be drawn willy-nilly throughout the foliage for a more chaotic and slightly more realistic vision of foliage.
7. Erase all the pencil marks you drew in Step 1.
