Just let momma do the work and try to interfere or mess with her as little as possible. The important thing is to keep any overly curious or aggressive or just plain nosy birds away from momma and the chicks...it keeps momma free from stress (and babies safer). If you have a community coop/nest...try to set up a little nursery area for her.
Keep food and water close, but not so close mom can tip them over into the nest. Don't panic if it looks like she is not eating or drinking. She is, she just isn't doing it when you are there. Broodies generally get up just once a day to eat, drink, and leave one gigantic stinky poo. She won't starve. She'll be fine.
I like to put in some Chick Saver electrolytes/vitamins in mom's water as I think it helps keep her energy up during the long brood, but you don't have to. High protein (18 to 20%) flock raiser or broiler chicken feed is better than layer feed as mom doesn't need the extra calcium as she is not laying and it gives her more protein during the brood as well.
Happy hatching

Lady of McCamley