Elements of Design
The 4 Elements Of Design
In this picture you can see even though the shapes of the couches, chairs, tables, and decor are a variety of different shapes they all go together complimenting the other shapes.
In the picture you can see that the differentiating texture of the two walls.
Picking out colors for a room is relatively easy. In this picture the white compliments the blue and the blue compliments the green. Just make sure when picking out colors that they go well together.
You can have fun playing with the lines in a room because being as all of the lines compliment the rest of them you can use all of the types of lines in just one room.