Work smarter, not harder
Part of making good casts comes from efficient casting. Allowing the rod to do the work by controlling your arm, hand, and wrist movements all can help you achieve tighter loops with great efficiency. Watch any good caster and they look like they are hardly working at it. Why is that? They have learned to control their body and arm movements reducing unnecessary motions that either rob the fly rod of load, or create wasted energy not needed to make clean casts.
A few key things to remember when casting for more efficient and effective casts:
Control your body! - A lot of people rock their body back and forth when casting. STOP IT! This unnecessary body motion does not help the rod more, as a matter of fact the rod loads less!
Tighten up your arm, hand, wrist movements. - The amount of distance your arm, hand, and wrist need to travel in order to properly accelerate the rod to a stop is shorter than you think. Good casters don't look like they are working at making cast right?! Cuz they aren't.
Pull your line off the reel before making the cast. - This is a pet peeve of mine. If you pull your line off the reel while casting you are doing two things. 1) Odds are you are pulling the line against the line guard wearing a groove into your fly reel and cracking or peeling your line. Unless you enjoy buying fly line twice a season I recommend you stop... or wait no keep doing that, I like selling fly line ;) 2) By pulling agains the reel while casting you are also pulling against your rod and either taking away from load on your rod, or impeding the rod from making smooth straight casts.
Reduce the amount of cast it takes to get your fly to the target. - The more you cast, the higher your odds of shit getting screwed up while casting. I believe that 90% of the time you only need to make 3 cast to get your fly to the target.
Practice. - Do I even need to cover this??