Write an article based on this "Sketch a thin line that will be the tree's trunk. Use a blending stump to blur the center of the tree. Define the trunk and branches with a very sharp pencil."
Use a 6B or dark pencil to draw a thin line on your paper. Make the line as tall as you'd like your fir tree to be. You can make your tree trunk as straight or curved as you like. Since you usually can't pick out the details when tree branches overlap, blend along the middle of the tree near the trunk. Try to leave the tips of the branches more defined so they stand out. If you don't have a blending stump, you can gently rub the paper with your clean finger. Go back over your tree with a sharp, dark pencil, such as a mechanical HB pencil, and draw over each branch so they really stand out. Then, draw the trunk between the branches much darker and shade in the base of the tree. Fill out the trunk so it's as wide as you like.