When planning a furniture layout whether starting from scratch or working with pieces you already have, it is advised to use a floorplan drawn to scale to plan the arrangement.
The floorplan is utmost importance when you are purchasing new pieces as buying furniture too small or too large for a space is an expensive mistake.
In this example with the circles, I determine the traffic flow through the space and identify areas for furnishings. This will start the creative process of how to best use the space.
The second step is to draw in furniture to scale within that floorplan. This example illustrates the furniture that will best fit in the space. Once a plan is drawn and the sizes of the pieces are determined it is then time to start shopping, or rearranging.
Other examples of planning for furniture arrangements.
This space is awkwardly narrow and long with a simple traffic flow. Two ample corners provide a place to put furnishings.
Sketches show two different ways the space could be furnished. There are a few other ways to use the space and those ways will develop once sketching begins.
There are online room planners one can use to get the process going. Start to think in "bubbles" first if you have a large open space or an oddly shaped room.
Once a furniture layout is to your liking, it is time to document the sizes so that you stay focused when shopping. If space is tight, it is important to stick with the sizes that on the plan; increasing a few inches here and there can have a negative effect on the overall flow.