What is a preparation step?

You may have observed standard ballroom dancers swaying from side to side for a measure before starting. If you started learning American style smooth before international standard, you would have learned that the man always starts dancing stepping forward on the left foot.

In international standard, we have a preparation step. It's a bit of movement to get the couple started moving and in sync before they start dancing. From the man's perspective it consists of a step to the left, a step to the right, and then forward on the left foot before starting a figure. For Waltz, the timing would be:
1. Step left
2 & 3: Hold
4: Step right
5: Hold
6: Step forward on left foot.

For Foxtrot and Quickstep, the timing would be.
1: Step left
2, 3, and 4: Hold
5: Step right
6 and 7: Hold
8: Step forward on the LF

If your first figure will start on the man's left foot, then hold for one more beat before stepping forward with the left foot.