Norman Rockwell is a beloved American illustrator who painted covers for the "Saturday Evening Post" for 47 years. Rockwell's illustrations are still widely circulated today in greeting cards, calendars and postcards. His paintings were idealized and sentimental, but they had mass appeal because they depicted people in everyday situations, doing everyday things.
Rockwell chose to paint subjects that put a spotlight on human behavior. Rockwell was famous for painting subjects that were sweet, humorous, idealistic and well-intentioned. His subjects were nearly always people in domestic settings, like homes, restaurants, doctors' offices and the workplace. Some of his paintings carried messages about current and world events, like World War II and civil rights. To choose a subject as Norman Rockwell would, begin with subjects that are close to you personally, who you will be able to portray with reverence, love and humor. The subjects should be people in domestic settings, doing commonplace tasks or enjoying themselves in ordinary ways.
Paintings that copy Rockwell's structural style will have a relatively flat background. Rockwell was an illustrator who painted primarily for magazine covers. It was important that his paintings were easily identifiable and that his subjects popped from the background. He typically painted either empty backgrounds of blank white, or flat backgrounds (such as a wall) behind his subjects. This is partially because when his subjects appeared in a believable and realistic space (as opposed to a flat white background of no real space at all), they were often indoors. Rockwell's subjects were always in domestic situations, depicted in homes and businesses, doing the things that people do indoors. Center your subjects in the middle or near middle of the picture plane, as he did. Rockwell did this because illustration itself is a medium meant to catch the eye and interest of a viewer spontaneously and quickly. By placing the subject in the center of the painting, Rockwell created a visually basic structure that appealed to the masses and was easily incorporated into the covers of the magazines for which he painted. When duplicating his style, the linear structure should be basic, not complex.
Rockwell's painting technique was overall realistic and highly detailed. He used colors that were often muted or mostly earth tones. Some of the characters in his paintings displayed exaggerated features and were similar to caricatures, adding an element of humor. Sometimes this humor stood in contrast to the more serious commentary underlying his paintings. This commentary was often about family, love and society. In his more serious paintings, the exaggeration of the subjects was lessened, or not present at all. Choose paints that are themselves natural and not wild or bright. You can use bold colors, but they should be earth tones. Use oil paint on canvas. Build up the paint in very thin layers to maintain tight control of the image. Photographic accuracy is essential, and you can use photographs for reference. Apply paint in a manner that does not allow the viewer to identify individual brush strokes. Brush strokes should be smooth and the paint should be applied in even layers. Sometimes, to add an element of caricature to his subjects, Norman Rockwell widened smiles, exaggerated poses or enlarged features like ears, noses and wrinkles. This is appropriate on a case-by-case basis, and this is something that you will develop with practice.