1. Unless you are casting a heavy fly, narrow loops are the most efficient, wind resistant and accurate loops.  
2. Loop size should be the same in the front and back.
3. Most advanced casters apply too much power, slow down and let the rod do the work.
4. The casting arc is defined as the angle change of the fly rod (near the grip) during the casting stroke.
5. Short distance cast = short casting arc. With my stiff rod and a 20-foot cast, the rod moves from 10:30 to 11 o’clock.  For a longer cast 10 – 1 o’clock (note all rods are different).  Increase (by a small amount) the casting arc when increasing the distance of the cast to keep the loop narrow.
6. To form a proper loop the casting stroke (forward or back cast) needs to be a smooth acceleration to an abrupt stop.
7. Any abrupt spike in power during your casting will cause the rod tip to bend excessively momentarily and result in a tailing loop (wind knot).  These often occur during the presentation (last) cast, especially with a punch in power just before the stop.  Remember smooth acceleration throughout your cast

DRILLS

1. Practice the horizontal casting drill, look at your loops, now look at your wrist and determine the size of your casting arc.   Vary the size of the casting arc ( 9-3 o'clock, 10-2 o'clock, 11 to 1 o'clock) and notice the change in loop size.  Narrowing the casting arc should decrease the loop size.
2. Practice the horizontal casting drill to get all loops to look the same as you are false casting.  Let the loops fall on the ground, see if the fly line is straight from the rod tip to the fly.  Practice this in the forward cast and the back cast. 

THE AERIAL MEND 

In situations where a post cast mend just won't cut it (think long and technical dry fly presentations).  After the forward stop (loop formation) on a normal presentation cast slowly “paint” (no need to rush) the rod to 45-90 degrees.  Practice to get the fly line in a straight diagonal from the rod tip to the fly.  Practice moving the rod to the left and right forming left and right mends.  Once you have mastered a straight diagonal fly line layout, then practice shooting (slipping) line after the stop.  This will increase the distance of your cast.  This cast is a proven fish getter, learn it, and use it often to replace the dreaded water mend.