How can I slow down the wind?

My house sits up on a small hill above the other homes here.The wind I get is crazy.It lifts my furniture,takes my umbrellas over the fence to the road.I was thinking that tress would help.This is the best way to describe the layout. backyard.Come out of door,to the right is patio,open area and neighbors fence.open door,go straight and that is where pool is,surrounded by bushes.Turn right and more open space then my fence.The road is on the other side of this fence.I have tied things down,the ground won't hold stakes well,because the earth is clay.Any ideas?I had a swing out there,the wind moved it forward,then sideways and it crashed through my bedroom windows.We are talking fierce wind here.Thank you for taking the time to read this.I'm thinking along the lines of landscaping differently????