Although there are no rigid rules for oil painting, it is good to know the different methods used by painters, so you can experiment with different ways, colors and compositions. If you are painting a simple theme, such as a landscape with a large area of ​​sky, there is usually no need for underpainting or a background drawing, except perhaps a line to indicate the horizon. For more complex topics, it is recommended to prepare a drawing that will set the composition, the main elements, and determine the balance of shapes and colors. With good planning at the beginning, later you get more freedom and spontaneity.

The background drawing can be done with a pencil or charcoal. To prevent the charcoal particles from mixing and getting dirty, wipe the surface with a cloth before painting. even if you sweep the surface, the outlines of the drawing will remain.

Underpainting is a type of subject to drawing  that is performed with a brush. It can be monochrome or colored. In both cases the dye is diluted with turpentine. The focus should be on the main surfaces, light surfaces and those in the shade, and avoid too bright colors.

Today’s painters usually use acrylic paints for underpainting because they dry faster than very dilute oil paints.One of the old rules is to paint “thick over thin”, which means that in the initial phase of painting you should use a fairly diluted paint (diluted only with turpentine) which becomes denser as the work progresses. diluted, thin paint applied over a thick, thick layer containing more oil, may crack as the bottom layer shrinks on drying.

But not all pictures are painted that way. Many are completed at once, with or without minimal underlying drawings and underpainting. This way of painting is called “alla prima”, and it is very free and spontaneous. When painting “alla prima”, thick spreads are used, and each color is applied as it will look in the end. The colors are mixed on the palette, but also by applying one over the other. This form of “alla prima” painting is called the “wet on wet” method, and it has been used extensively by the Impressionists, especially Claude Monet in outdoor painting. If you haven’t tried oil painting yet, this method is a good start because it gives you an “instant feel” for this technique.

This method applies an uneven layer of paint over a dry underpainting that has relatively little oil so that the lower color can be seen through the applied paint. Skilled hands with this technique can achieve some of the most amazing effects in painting, and achieve the impression as if the painting is veiled.
It’s a great way to change color without sacrificing its vibrancy. Even the applied layer of paint can be changed by the action of the sub-image as if it was intended in advance. For example, a flat dark red sub-image can be softened with a brighter red, pink, or even some contrasting color. The surface texture of the paint is more challenging than the one below and more effectively contributes to the illusion of the painted theme.
Dark colors can be applied to lighter ones, but it is much better to do the opposite.
One way is to dip a wide flat brush into the paint which then drains well and gently pulls across the surface leaving a thin film.
The thick undiluted paint is applied in a circular motion with a round brush with a lot of paint that is held quite upright. Or a fairly wide and flat brush dipped in a thick paint is dragged across the surface so that a smudged, broken layer of paint remains. Tapping with a round or fan-shaped brush creates spot spots.

The color can also be softened with your fingers, the edge of your palm, a cloth, a sponge, or a spatula. The coarser the texture of the fabric, the softening of the colors will be more effective because most of the color will remain on top of the weave.
We need to experiment with paints of different densities on different surfaces and with different accessories that can be held in different ways, we will discover what kind of effects can be achieved.