I have found it is best to use a coarse grind to prevent the screen in the plunger from becoming clogged. Too fine of a grind can lead to a clogged screen and more sludge in the bottom of the cup. I like to start grinding the coffee beans just before my water starts to boil. I use an electric kettle to boil the water. It is also a good idea to use filtered water to make sure all you taste is the coffee. The temperature of the water should be between 200 and 205 degrees. I let the water boil for just a moment then open the lid for the kettle as the beans finish grinding. I then put the coffee grinds in the French Press and let the water cool.