Feet position on a surfboard is critical. From the moment you pop-up until you reach the white water, your feet will be constantly working and shifting. How do you stand up on the board?
In surfing, feet mean balance, control and speed. With the help of your hips and arms, your feet will swing you through the optimal surf line. That is why feet positioning on a surfboard is a must-have lesson.
Fortunately, there's a golden rule. Your front foot should always be in the middle of the plank - lengthwise and widthwise - regardless of what size your board is. That is the classic, general position.
Your front foot is controlling the board and should always be placed over the stringer, except when you're maneuvering in the waves, no matter if you're a regular, goofy-foot or switch-foot surfer.
The same rule applies to your back foot. The standard mode tells us that your back foot should be positioned on the opposite side of the front fins. If you use a traction pad, it will be well over the grip.
If you want to turn quicker or adjust it for a maneuver, then your back foot will slide back towards the tail. This slight adjustment will loose the board in critical wave sections.
In advanced surfing, both feet will be shifting around over the surfboard. In other words, you're constantly adapting to different situations. For example: moving forward for barrels and aerials, and moving backward for lip attack.
If you're looking for speed, your feet may move forward in the nose direction. If you need to carve hard or go straight off the lip, then your feet should move backwards.
If you're riding the right surfboard for your weight/height, you'll notice that your feet will be about shoulder width apart. Get used to your feet position when taking off, in order to avoid unnecessary correction during each ride.
As a conclusion: your back foot is usually the brake and your front is the gas pedal. Keep up the momentum and get your feet on the right place, next time you paddle for a perfect wave. Small changes make miracles.