1. Draw the outline of the structure.
2. Squint to see the overall light-dark relationship. Simply divide the black, white and gray parts into three parts, and arrange the black and gray parts roughly together with 2B. After writing one article, use 2B to lay another tone with lines at different angles in the black part (the first article is a small acute angle, which can change and unify the general direction of lines). In this way, a simple black, white and gray color code came out. If the black area is large, 2B will be exhausted.
Open your eyes wider, but don't look at that part. Look at the relationship between light and shade a little, not the part. This refines the levels of black, white and gray until the tone level is relatively complete. Then describe an object.
4. Depicting a local single object, grasping it on the critical boundary line of light and shade, and making up for it. The place where shadows meet objects is also darker. Highlight the outline and three-dimensional sense of the object. The details and main places should be described carefully, such as the bottle mouth and the concave part of the upper part of the apple. The thin part should be drawn with sharpened HB or 2B.
5. In the process of painting, keep taking a step back to see the overall effect. Pay attention to the overall color block. For example, no matter how dark the dark part of white cloth is, it can't be as black as the dark part of black cloth.
6. The unimportant part in the distance, that is, the imaginary part we often say, should use light and loose lines. Clear lines should be used for the main part and the real part in front. Hard and smooth ones should be straight and clear, such as stainless steel. Rough, such as pottery, can use loose and thick lines.
To achieve the above points, sketch should be no big problem. Of course, the premise is that there is no problem with the appearance.