One of the tools I use for better running has nothing to do with my feet; it's my ears!
Great running form is nearly soundless. Each footfall should land with barely any noise, signaling that there is no wasted energy directed into the ground and that as much energy as possible is driving the body forward. Also, it means that there is minimal shock transferred back up the leg and into the body.
Every time I run, I strive for soundless running. I try my best to train my legs to have light footfalls, even while they are cycling fast during sprinting.
Whenever I start to hear louder thumping, I know I'm doing something wrong. Maybe I'm getting tired, or getting lazy, and not concentrating on how I'm placing my foot down. Perhaps I'm moving too fast and I need more training for light footfalls at higher cycle rates. Or sometimes I hear a louder thump from one leg than the other; that means that one of my legs is not moving in the same way as the other - something that needs to be fixed!
Training for light footfalls can be difficult. I have to pick up my leg in order to run, but I don't want to pick it up too much or else I raise the chance of thumping the leg on the ground. I try to glide my foot across the ground as low as possible, and the gently place it down on my forefoot as my body moves forward and this motion is repeated on the other side. Sometimes my legs are moving too fast, like during sprinting or tempo running, and I need to focus even harder on placing light footfalls.
As I glide my foot forward, I also strive to maintain an even head height and not let it bounce up and down. Bouncing means that I'm wasting energy moving my body up when it should all be directed towards moving my body forward. Inevitably, bouncing leads to louder running as the legs must absorb the energy of the body coming down on each step.
Hills can be challenge, with downhill being harder. I have to aim my foot at an angle down the slope of the hill, while leaning over the foot to keep them under me. The dropping away of a decline means that I need to compensate for that when my foot moves forward to take a step, but also down the slope of the hill.
Then, training for repeatability of light footfalls over time is next. Maintaining light footfalls may be OK for short runs, but training to maintain light footfalls over the length of a marathon means extending my neuromuscular training over time. When we get tired, the legs don't respond as well and light footfalls may be the first thing to go.
Soundless running is really important to minimize the chance of injury. When you place each foot down with minimal sound, you are landing with minimal shock transmitted back up the leg and into the body. Over time, lots of shock transmitted up the leg will lead to all sorts of problems. Silent running will minimize that shock and allow you to run injury free.
Therefore, whenever I run, my ears are attuned to my footfalls and my goal is to run as silent as possible.