Swim regular freestyle. As you take a stroke with your right arm, keep your left arm extended forward in the water. Complete the stroke with your right arm and after it enters the water above your head, tap your left hand. This signals the start of the stroke with your left arm. Keep your right arm extended forward in the water until the left stroke is completed and hands tap together.
Reverse Catch-up Drill (R-Catch-up)
Push off the wall with both hands on your thighs. Take a complete stroke with your right arm, when it completes the rotation and touches your thigh, that is the signal to start the next stroke with your left arm. Continue alternating arms, with the non-stroking hand resting against your thigh.
Pause your stroke for a moment when both hands are forward (like normal catch up drill) and also when each hand reaches your thigh before exiting the water. This drill can be very slow going, add fins if you have a hard time staying afloat or making the interval.
Catch-Up w/Board (Catch-up W/B)
Use a sideways kick-board to perform the drill above. Keep your hands shoulder-width apart and exchange the board from hand-to-hand between each stroke. This also helps prevent crossover in your normal freestyle swimming.
Swim a lap of freestyle while you drag your thumb along the side of your leg as you lift your arm out of the water.
Finger-Tip Drag (FTIP)
Swim regular freestyle. When your arm is out of the water keep your elbow pointed toward the sky and your fingertips pointing down toward the water. Allow your fingertips to drag through the water from your hips all the way past your head.
Kicking Drill (K)
For the kicking drill I recommend the side kick. To do this keep one arm extended in front, with the other arm at your side, maintaining a constant kick and rotating your head to breathe. With each length of the pool switch which arm is out in front. This is a foundational kicking drill that develops balance, leg strength, and the ability to breathe on your side. Also, being on your side forces your legs to catch water as opposed to air, giving you a better leg workout than, for example, kicking with a kick-board.
Single-Arm Drill (LT, RT)
For learning the correct pulling motion. Grasp a small kick-board in your left hand and extend your left arm above your head. Swim a lap of the pool with just right arm strokes. This will allow you to focus on a perfect underwater pull with your right arm. Switch arms and swim another lap.
Underwater Recovery Drill (UW)
Swim freestyle but do not let your arms exit the water at the end of the underwater pull. As your hand reaches your thigh, bend your elbow and slide your hand forward along the side of your body. This is very similar to doggy-paddle but with an entire underwater stroke. Keep your head in the water and breathe to the side like normal.
Fist Drill (Fist)
Swim regular freestyle. Ball your hands into fists and work on high elbow catch and pull under the water.
Sighting Drill (Sight)
Practice lifting your head up while swimming. The main purpose is to help you swim a straight line in open water. Before swimming always remember to first to select something in the distance that is easily visible from the surface of the water.
Tarzan Drill (Tarzan)
Swim freestyle with your head out of the water. Look forward as if you were sighting a buoy or landmark in open water. Keep your head out of the water for the entire 25 to strengthen your neck muscles for triathlon swimming!