How do you control it? WSAD/arrow keys/mouse?
If it's by mouse I'd create two triggers:
1. When the unit is issued an order at point, the trigger will save the point and run the second trigger. It will also disable the second trigger at the beginning so your unit will have only one movement trigger active on it.
2. Whenever the unit gets close to the point saved in the first trigger, calculate a new point further away from your unit and order it to go there.
This isn't perfect, and one cliff in the unit's way will change its direction, but it's a start.