For my two year old who has been throwing fits all day for several months, I made a picture chart with our daily schedule. The structure is helping him a lot! The pictures make it easier for him and his brother to know what's coming next.
We have also made a mandatory "quiet time" where the kids have to be in their beds and be quiet for 30 minutes (I set a timer so they know at some point the time WILL end). I give them a small box with books, puzzles, and little toys in it that they can play with. These boxes are put away and they are only allowed to play with them during quiet time.