Start with your left foot and march in time. The left foot will raise from heel while keeping the left toe firmly planted into the ground. As the left foot comes down, the right foot comes up. Practice marching in time, while keeping your upper body still. Avoid the tendency to wobble back and forth.
Step out with your left foot and keep your toe straight out in front of you. When you step forward your toe should be straight and form a 45-degree angle with the ground. Follow in the same manner with your right foot.
Plan each step to ensure that the left foot always lands on the first beat of the music. Most marching band music will be in four; in some cases where the music is in three, the left and right foot will alternate on beat one.
Avoid the tendency to bring your knees up too high when marching. If you have a drum that interferes with your movement, you will have to be careful to raise your legs only so high that they do no hit the drum.