What factors shift the Aggregate demand curve to right and what factors shift the AD curve to left? 

AD shifts to the right when any component of AD enhances autonomously; e.g., if

a) Consumers become more willing to spend at each price level;  

b) There are autonomous enhances in investment due to better business prospects;

c) The government spends more, or decreases taxes; net exports rise at all prices (due to say an increase in the quality of domestic goods relative to foreign goods). If above mentioned facts are reversed, AD will shift to the left.