Taken from wikipedia1.
Short, thick strokes of paint are used to quickly capture the essence of the subject.
2.
Colours applied side-by-side with as little mixing as possible, creating a vibrant surface. The optical mixing of colours occurs in the eye of the viewer.
3.
Grays and dark tones are produced by mixing complementary colours. In pure Impressionism the use of
black paint is avoided.4.
Wet paint is placed into wet paint without waiting for successive applications to dry, producing softer edges and an intermingling of colour.
5. Painting in the evening to get
effets de soir - the shadowy effects of the light in the evening or twilight.6. Impressionist paintings do not exploit the transparency of thin paint films (glazes) which earlier artists built up carefully to produce effects.
The surface of an Impressionist painting is typically opaque.7.
The play of natural light is emphasized. Close attention is paid to the reflection of colours from object to object.
8. In paintings made
en plein air (outdoors), shadows are boldly painted with the blue of the sky as it is reflected onto surfaces, giving a sense of freshness and openness that was not captured in painting previously. (Blue shadows on snow inspired the technique.)
MONET'S STYLEBROKEN COLOR: to achieve the actual sensation of light itself in a painting