Measure and Mark the Height of the Wainscoting
Once you have the room prepared for wainscoting, draw a level line on the wall to mark the top edge of the wainscoting. Start from one end of the wall and then use the spirit level to mark the required height of the top of the wainscoting. Since you will be installing base trimming on the bottom part of the wainscoting, therefore even if your floor is not level, it can be camouflaged.