In martial arts, footwork is very important. The farther along one gets in training, you'll find the greater sensitivity you have towards the dynamics of walking and placement of balance. This, obviously, expands into how to walk more silently, more stealthily for Ninjutsu training, but it all has a foundation in movement and how to move well.
One thing you can explore, just from a basic perspective, is when you are walking, walk slowly in the beginning and practice placing your toes and the ball of your foot down before you actually place the heel down and walk shifting your weight slowly, picking your knee up, placing the toes down, almost like you're going to place your toes onto a rug or into some grass, under some leaves, and then letting the weight come down slowly onto your heel. Practice shifting that weight and explore how you can move more efficiently your balance between one foot and the other using this type of movement.
You'll find that as you get better and better at this that you're more aware of how to walk and to be more silent. There is just a little bit about how to walk in martial arts and in Ninjutsu.