1. Le Corbusier, Sketch of bulls and peasant houses near Chandigarh, dated March 1951; Courtesy Foundation Le Corbusier, Paris.
2. https://www.kooness.com/posts/magazine/top-11-most-iconic-and-famous-sketches-ever-made

1. Pablo Picasso
2. bull sketches
3. https://www.pinterest.com/pin/317503842472885390/

1. Salvador Dali
2. horse sketches
3. https://www.huffpost.com/entry/salvador-dali-diary_n_572235c7e4b0f309baeffb47

1. Victor Vasarely
2. Sketch-[birth]-1955
3. https://www.proantic.com/en/display.php?id=971523

1. Bridget Riley
2. early art school drawing on paper (detail)
3. Scottish National Gallery
4. https://artmag.co.uk/scottish-national-gallery-rsa-bridget-riley/

1. try to see as many things as possible
2. try to see in different ways
3. try to see something new, make a discovery
4. try to experiment with different ways to express it (gesture, contour, abstraction)
5. try to be intuitive

don't:

1. decide if it's bad or good
2. get fixed on one viewpoint
3. think too much
4. give up