How does an artist start a painting or drawing? First, they find a subject that has a compelling interest which will motivate them to say something that makes it a worthwhile subject for artwork. An artist is not a copy machine. A lot can be done with photography, computers, and printers, and if a mechanical reproduction is sufficient, there is no need to paint it. The camera is a slave to what is in front of it. The artist interprets what they see. They do not duplicate it. The subject in front of them is seen by the eyes, modified by the brain, and made by the hand. The indescribable process of creativity determines the color scheme, composition, and treatment of the subject.
After choosing a subject, an artist determines the composition. Nature is always a great reference, but that is all it is. A landscape may have a rock or tree in the wrong place, or something will be the wrong size. The artist eliminates or modifies elements of a scene to suit their composition.
Does this apply in portraiture? Certainly. Portraiture is capturing the essence of a person by capturing their physical likeness and spirit. The placement of the features must be specific to the individual, but the pose, body language, lighting, and setting are determined by the artist to create the feeling of the person.
We've all seen life masks (or death masks), and they never look as real as a well-done bust. By definition, they are more accurate than the bust, since they came directly from the subject, but the artist adds feeling, which brings them to life.

These are abstract ideas, which may be difficult to understand. Lets have an example. Here is the beginning of a still life showing two orchids. This picture shows the plants in the background, on a fabric backdrop. There are brushes, paints, a charcoal stick, and a computer print on the table. My canvas is on an easel, and I've finished the charcoal drawing.
How did I get to that point? Years ago, I would have made thumbnail sketches in oil or pastel to determine the color scheme, composition, and values. Today, I do most of this with a computer.
Note that the orchids do not look like the computer print, and the drawing has subtle changes from the print. I'm changing all of these as I go along- improving the picture, I hope! Lets look at some enlargements which will help you see these changes.
Here are the orchids in front of a grey backdrop. Note the Phalaenopsis (white one) foliage is turned ninety degrees to the blossoms.



I flattened the background to make it less confusing, and combined several pictures in Micrografx Picture Publisher. The Phalaenopsis blossoms are parallel to the foliage. I doubled the number of blossoms and changed the angle of their arch. The Cattleya (purple one) is similar to the photo, but I added a front view of the blossoms. Where did the red ones come from? I added them from photos of a plant out of bloom, and some pictures from an orchid show. Note the two top blossoms look very similar. I flipped one when I pasted it into the picture.
The charcoal drawing has more graceful lines than those done by nature or the computer.
I omitted two steps in this explanation. One was selecting the medium. This subject needs color, and oil is the best color medium, so I knew I would do an oil painting. It could also be done in several other mediums-pastel, pencil, charcoal, or etching, but the final effect would not be what I want. Oils have a richness other mediums lack.
The other decision was to choose a size and format. The photo of the plants is almost square, so I could have done that. The composition didn't look interesting, so I added the red flowers (Pragmipedium), which created a vertical composition. I could have made a horizontal one, but like the lines created by the Cattleya leaves pointing to the red flowers, as well as the Phalaenopsis also pointing to them.
That determined the format. I decided to paint this about life size, so I settled on 20 by 16." The flowers will be slightly larger than life size, and will look impressive. If I had done them as a 7 by 5," they would look like a knickknack, and if I did a 40 by 30", they would look like a cabbage head.