There have been several commentaries adding pedal pads to get proper heel and toe. I have found the shoes you wear are a big factor in how difficult or easy it is to heal and toe.

Here is the plan for my size 10 feet:

For a Formula Ford, I like wear Nike Cortez in a size 10 narrow and fairly thin Nomex socks to have room to operate the pedals. I can't walk comfortably in these shoes BTW. They have a rounded heal, a very small, narrow sole. As good as they work in a Formula car these shoes are next to worthless in a passenger car with their wider pedal spacing. Nor can I drive any car fast in dress shoes.

For a Subaru Impreza I like to wear a set of wide, flat bottom, high top gym shoes or boots and heavy cotton socks. These shoes have a very heavy square edge around the wide sole and grippy, flat rubber bottoms. Just the ball of my foot and the big toe rests on right portion of the brake pedal. The shoe edge and width prevent the foot from slipping off the brake. The heal of my foot maybe has a comfortable 15 degree angle to the center of the car up from the floor.

I place the ball of my foot , the edge of the ball firmly on the edge of the brake pedal. The motion to blip the throttle for a down shift is more of a rolling side motion at the ankle while the ball of the foot is pressing the right hand portion of the brake pedal. This permits keeping the brake pressure steady with the muscles of the leg while using the (isolated) ankle muscles to control only the throttle motion. The throttle is touched by the outside edge of the shoe well above the heal of my foot. This makes for smooth steady braking by leaving the leg muscles in uninterrupted control of the brake. Conversely it also permits easy ankle control of the throttle against the force applied to the brake pedal by the ball of the foot.

This use of the throttle with the outside edge of the shoe permits extremely smooth transition from brake to throttle in a high angle corner where braking is very important to turn the car and the timing of the throttle application and amount is critical to retain control. You pile into the corner under braking and relax the ball of your foot up off the brake pedal while rolling into the throttle with the outside edge of the foot. This motion, its degree and timing, can be more important that steering input at that moment.