The first thing to keep in mind is to perform the plank correct. Even though it is one of the basic exercises, most people perform it incorrectly. This reduces the benefits of bodyweight exercise. Here is the right way to do it.
Step 1: Come to the table-top position with your knees below your hips and your wrists below your shoulder.
Step 2: Lift your knees off the ground and straighten your legs to bring your body to full extension.
Step 3: Your feet should be shoulder-width apart and your palms pressing against the ground.
Step 4: Elongate your spine