There are two schools of thought about whether an artist should use an art projector or other similar devices to help create art. Art projectors, when use correctly, can help an artist lay out a piece of art. When creating a portrait, it is very helpful to get the placement of the eyes, ears, and nose. An art projector can help with that, and also help get an accurate shape of the face. All these elements make a portrait look like the person you are trying to draw. What they can't do is give you all the detail you need. If you have some basic place markers for important features, you can relax and enjoy filling in the details.
Select the photo you want to use for the portrait. If you don't have a digital file, scan it, and open it in your photo editing program. Most photo editing software has a choice for a "poster edge" or something similar that will create pronounced outlines in the photo. This will make the projected image easier to trace. Change colour to black and white to better see the contrast. Print the photo the correct size for the projector. An inexpensive craft projector uses a 4-inch by 4-inch photo. Print the photo the same size as the finished drawing for reference.
Set up the paper and projector to reduce distortion as much as possible by using a wall or vertical surface to tape your drawing paper. Place the projector on a flat surface. You will need a room you can darken. Place the photo under the projector opening and turn on the projector, then turn off the lights. Adjust and focus the projected image by adjusting the lens and/or moving the projector farther away or closer as needed.
Use a soft pencil that won't leave indents in the paper. A 2B is a good choice. Draw lightly. If you leave indents in the paper as you fill in the area it will leave a line even if the graphite is erased.
Draw the essential features. Avoid getting hung up on the details. Look for areas of strong shadows and highlights, and make sure you outline these areas as if the shadow and highlights are a feature on the face. They help give shape and definition to the face.
Take the drawing paper down and place it on a smooth drawing surface. If you don't have a drawing board, a piece of Masonite will work. Any irregularity in the drawing surface will appear in the drawing as you work over that area.
Finish the drawing by filling in the details. Use a circular drawing technique that overlaps the pencil lines, so the fill looks even. Vary your pencil hardness and softness to achieve the correct results. Use hard pencils H to 8H for light areas, 8H being the hardest and lightest. Use soft pencils B to 8B for dark areas, 8B being the softest and darkest. Use an ebony pencil for the darkest areas. Don't be afraid to use white space for white. An eraser can be used as a pencil to create light areas.
Stand back often to look at your work to make sure your areas contrast enough and that the detail is showing. Since you have the essential lines traced on your paper, finishing your work is a lot like colouring, but much more rewarding.