Standing in front of the group, begin by pointing up in the air towards the right or left. Follow up with verbal prompts so that athletes follow steps appropriately. When you point your finger in a certain direction, outfielders should dropstep in that direction. When you yell "crossover," athletes should take their crossover steps... and on "go," athletes are to take two or three running steps.
Move athletes into one line with the first outfielder stepping out in front of you. Begin by pointing a baseball in one direction (right or left). The athlete is then to dropstep and crossover in appropriate direction as you reach back and throw an easy pop fly.
Involve fly balls off of the bat only after fundamentals are solid.