i have a cottage i want to insulate although it isn't heated in the winter but in the fall and spring it is cold so i use a electric heater to get the chill off what kind of insulation is best that won't hold the moisture and cause mold

The "best" insulation really varies with your project, but here's an article that will give you a good overview. Some of the variables are -- do you have access between the walls, what's your budget (blown in insulation is a little more), etc.

http://www.oldhouseweb.com/stories/Detailed/10169.shtml