It looks like you've placed you house on a slope, which isn't always visible when you choose a lot, or place a lot. Smoothing the lot beforehand doesn't work. So, what you do is put your house in place and use the terrain tool that smooths/softens the edges. It will take a bit of work and your house STILL might not look right. The best way I've found is to put the house on a lot that is too big for it. So if the intended house was a 30x20 make or use a lot that is the next size up. This will place the house right in the middle of that lot so your path to the house and/or driveway will have to be extended but it will make the edge smoothing easier and more normal looking. Otherwise your house winds up either sunk in the ground, perched on a steep, angular shelf, or both depending on the lay of the land.
I'm running into this a lot as I remodel Twinbrook to suit my aesthetic desires. Swamps do not appeal to me so I'm trying to turn it back into a viable and attractive community. It's quite a challenge and means adding a lot of lots where there were none.