Running and cycling efficiency certainly can be improved through an evaluation of technique; however, swimming is even more reliant on proper form to be successful.
There are three main parts of an efficient freestyle: entry, catch, and pull. Upon entry, your hand should not cross the center of your head; your arm should be almost fully extended, but not too much, and your hand should be in such a position that it appears like you are reaching into a high mailbox instead of turning your thumb. Once your hand enters the water, use a high elbow catch to maximize the amount of water you will push back, rather than down. Your elbow will hinge, using the full power of your paddle that includes your hand and forearm. Push the water back until your hand exits the water.
Think of these three things to improve your stroke and consider a swim analysis. I’ll post a video of my swimming technique soon. In the mean time, contact me if you would like a swim analysis of your stroke. Swim happy! And fast!