No Preheating Required
A slow cooker should never be preheated. Simply put the stoneware container in the slow cooker base, cover and set the desired cooking temperature.
Slow Cooker Care
Do not add cold water to slow cooker immediately after use as this could cause it to crack. Either add warm soapy water or let the slow cooker reach room temperature before cleaning.
Using a slow cooker is electrically economical since it requires less energy to cook the recipe in a slow cooker than on the stove or in the oven.