Nurturing a keen observation power is a child's play. Observe a person with full concentration while talking to him; later on ask yourself," What was the colour of his dress? What were the distinct marks on his face?"
While visiting a place observe all the details including minor one; Recollect later on what you observed there.
Find what you missed during your first visit when you visit the same location again. This simple technique will increase your observation power with supersonic speed. You will also get a sharp memory as a bonus.
To make the game more interesting and lively, you may relate and discuss your observations with your friends.
Have you ever tried to recollect all the articles and their placement in your bedroom? Do it and you will be amazed.