The first step is to clear out all of your furniture and clean the floor. Use a hardwood floor cleaner or a mix of water and white vinegar. Use a terry cloth mop to wipe the floor.
Use sandpaper to sand the perimeter of the room working over each board until the finish dulls.
The next step is to scuff-sand the finish. Move a buffer from side to side in the direction of the grain.
Once you finish sanding, vacuum the floor to get rid of the dust and debris. Then start along the edges by spreading strained finish with a brush.
The last step is to roll out the poly. Use a long-handled roller with a ¼-inch nap cover. Go with the grain first and then across it. Wait 3 hours before applying another coat and wait a week before moving the furniture back in.