Which foot do i drive with in bball?

ok so im having problems in basketball. When i drive to the hoop, i get called for traveling. So what foot do i drive with cause it seems like i don't go that quick to the hoop. like when i drive to the hoop on the right side do i lead with my left foot or right foot. Also i am 6'1 and still can't dunk let alone touch the rim. Any exercises that can help increase my vert?