First time Duck hunter!!!!

[unionjack]

What is the essential list of supplies needed for a duck hunting, i have never been. I have been invited on a goose hunt, but i have always held an interest in duck hunting. Shotgun wise i am planning on a pump 12 ga. useing 3" shells. Benneli nova to be specific. I live on lake Erie in ohio, everyone i know hires a guide and they go out on the lake and hunt open water. I had never heard of that before. I would rather hunt marsh area( im not to keen on boats) Do i need to look at getting a dog ? I have been considering that for some time, not just for hunting but companionship as well. What are the bare esentials im going to need to get into this great sport?