How do I know if my power drill needs to rotate clockwise or counter clockwise to drill forward?
Think back to your high school physics class and use the Right Hand Rule.

Lay the drill bit across your palm, with the point towards your thumb.  If the fingers curl around the bit (or screw) in the direction of the threads, then it's a right handed bit.  That means you turn clockwise to drill (from the perspective of looking down on the work).  



This rule is also extremely helpful when you are working upside down and backwards trying to tighten something.  Point your right thumb in the direction you want the screw or nut to travel, and turn the object in the direction your fingers curl to tighten.  

When in action, Clockwise/Forward looks like this.