Da Vinci introduced different methods of using a paintbrush that include:

• The Sfumato Technique:

This helps soften the colours by using a dark glaze around the edges of some objects. This creates the effect of someone being obscured by smoke/mist.  This technique was used for the Mona Lisa especially around the eyes.

• The Chiaroscuro Technique:

You would use contrasts of light and dark to create a thre dimensional like effect.  Da Vinci used this technique in his drawing of The Study of Arms and Hands. Many people still use this effect these days.