As many fisherman know when the water gets clear it is time to use lighter line. The video below will show you how to put the line on a spinning reel properly. No pencil needed.
Remember the new line's spool should face the same direction as the spool on your reel. By doing this your line will not become twisted.
The only additional step I would suggest is putting the line through the eyelets. When doing so it will put an even amount of pressure on the spool thus reducing loops.