Find out what the 12 tenants of Landscaping Design are. Learn the details and interactions of them all. Be creative and know the right plants that belong. Don't be afraid to think outside the box.
If you don't seem to be very good at laying out a design, chances are no amount of schooling will help. Similar to being an artist or singer. I can't be train in either field.
I give suggestions to get them to think about what they want, tell them about possible plants that would give them what they want. But the one thing I can do with excellence is plant what is ultimately chosen and have it thrive.