Get a rough idea of where you want specific pieces of furniture to go. Sketch it out on a piece of paper or use an online program designed to help you plan a room. Planning can help prevent unnecessary heavy lifting.
Determine what the focal point of the room is going to be. This is the feature that is most attractive and around which furniture will be placed. It may be a fireplace, picture window or beautiful piece of art. You can tell a room that has been arranged well by the fact that guests are able to sit and visit, while also viewing the focal point.
Once you have a plan in place, try it in the actual space. There's no rule that says you have to stick with your original idea. Change it as often as you need to until the room feels right. The general rule of thumb is that you should easily be able to move from one side of the room to the other without bumping into any obstacles.
The sofa is often the largest piece of furniture in the room. Place it first. Sitting the sofa with its back to the largest wall is a good way to begin. It should be facing the focal point. Add other pieces of furniture, keeping in mind that anyone sitting in the room should be able to see the focal point. That may mean placing a love seat or a pair of chairs at a 90 degree angle to the sofa or directly across from it.
While you're rearranging a room is a good time to take a hard look at what you have and what you actually need. You'll find that if you edit some of the unneeded pieces out of the room the finished room will look more spacious and feel more tranquil. Ask yourself how many people are normally in the room at one time. If that number is three or four, have enough seating for three or four. If guests come by, you can always bring other chairs in from the kitchen or dining room. The idea is to take advantage of every square inch of space by including only what you actually need.
While you're editing furniture, make it a point to edit accessories. You can always rotate things out of the room, store them away, and bring them back as you rotate other items out. Make sure that accessories like area rugs, candlesticks and artwork are in proportion to the room. If you have a very large wall, hang a large piece of art. If you're dealing with a small fireplace mantel, avoid large accessories as they will only make the mantel look smaller.