In the meantime, consider these thoughts about casting:

• Find a good video or textbook on fly casting and watch/study conscientiously.
• Practice.
• Practice seriously, for short periods of time. When you're practicing, cast with 30 to 35 feet of line.
• Be certain that your fly casting outfit (fly rod, ree and line)are balanced. "Balanced" means that weight designations on each match; i.e. a 5-weight line to a 5-weight rod. Matching, for instance, a 4-weight rod with an 8-weight line will result in an inefficient relationship between the two(i.e., because it's too heavy, the 8-weight fly line will "slow down" the action of the rod.)
• Don't grip the rod too tightly.
• Always stand at a slight angle to target so that your body is able to "move through" the cast.
• The rhythm of casting is the time it takes for the line to straighten out during the forward and back cast. To cast efficiently, the line MUST straighten out at the conclusion of both casting motions.
• Understand the casting plane. The cast is most efficient when the movement of the rod from the start to the finish of the cast is on a plane or straight line, usually a plane that is parallel to the ground.
• Power is applied crisply at the very end of both the forward and back cast, not during.
• The fly always goes to where the fly rod points when it is stopped at the end of the forward cast. Stop the rod above your target (the area of the fish) so that the line and leader have time to straighten out before the fly is delivered.
• During the back cast, concentrate on "elevating" the line slightly so that it will drop down to the desired casting plane.
• Always cast with a manageable length of line; if you get too much line out (usually more than35 to 40 feet) your casts will fall apart.
• As you finish your forward cast and deliver the line, leader and fly to target, don't give upon your casting stroke; stay in command and push through (the thumb of your casting hand plays an important role at this point, helping to push the rod through to a brisk completion of the cast)to make sure there is sufficient power left to turn over the line and leader crisply.
• Always be aware even when practicing of how and where you want the fly to land.
• Once the cast has been made, lower the rod to fishing position and transfer the line from your left hand to behind the index and middle fingers of your right hand, which is stripping position(opposite if you cast with your left hand/arm).
• Once you start to get comfortable with the mechanics of casting, get a feel for the part your fly rod plays in casting. Your rod is built to participate actively in the cast; give it a chance to do that. Forcing the fly rod to execute any cast will be counterproductive.
• If you are not casting well; if you are experiencing fatigue or stress in your wrist, forearm or shoulder, take a break and rest.