it depends on if your left handed or right handed and how fast or slow the pitcher is throwing
if you are right handed while facing the pitcher you stand on the left side of the batters box. right side if you are left handed.
if it is a fast pitcher stand toward the back of the box to give yourself more time to read the pitch and swing at the ball. slower pitcher towards the front of the box
if you are bunting stand in the front so if the ball goes straight down it wont hit the plate
a batters box is 4 foot by 6 foot.
Page 4 of the Official Baseball Rules shows a diagram of the infield, stating the batters box is 4 feet by 6 feet.
According to http://www.infoplease.com/ipa/A0113430.html, the batter's box is 4 feet X 6 feet. In major league baseball the batters box is 60 inches long and 40 inches wide.
On Base Percentage
the size of the batters box goes from the batters knees to his shoulders and a width of 17 inches
Intentional Base on Balls