Remember how strange it seemed to learn that your training aircraft is steered on the ground with foot pedals, and the throttle is worked by hand?
You absorbed those surprises, made the mental adjustment, and got on with learning to fly. (You may not have realized it at the time, but that was your first brush with the law of primacy, a concept that speaks to the power of first impressions in learning.)
There were similarities, too, between aircraft and your familiar modes of ground transportation. On most single-engine aircraft, the brakes are foot-powered, although to use them correctly, you learn to apply pressure to the proper portion of the pedals, because they also control steering and rudder.
Another revelation was that aircraft brakes function independently. If a taxi turn that you have initiated with nosewheel (or tailwheel) steering needs to be tightened, a touch of brake in the desired direction does the job. Mostly, however, you taxi with minimum power and the steering function, avoiding excess braking.
Nosewheel steering also guides the takeoff run until rudder becomes effective; the reverse applies during a landing roll. Braking—except in aircraft with a castering nosewheel—is usually deferred until needed for exiting the runway or coming to a full stop.
Most trainees master the technique quickly, but it only takes a distraction or stress to cause a misstep, with several possible consequences. Inadvertently riding the brakes during takeoff delays acceleration, reducing the safety margin on takeoff from a short runway. On any takeoff, brake pressure applied asymmetrically could induce a swerve, or a complete loss of control.
On landing, touching down with a brake pedal depressed could cause directional control problems or even blow out a tire.
Maintain the proper pedal pressure and position by being seated comfortably at the controls, and by adjusting your foot position on the pedals depending on the operating phase in progress (use a forward motion for steering or rudder, forward and raised to add braking).
"As the airplane starts to roll forward, the pilot should assure both feet are on the rudder pedals so that the toes or balls of the feet are on the rudder portions, not on the brake portions," says Chapter 5 of the Airplane Flying Handbook.
Then relax and fly with a light touch on all the controls.