What early signs does the reader see that society is breaking down and their attempts at civilization are not working? mention their clothes and man's capacity for good and evil
If one is asking about the boys' tentative attemts at forming a society on the island and not society at large, there are plenty of examples: physically the boys' hair along with their clothes have become ragged and dirty, their toilet habits have come carelessly close to their bathing area, they have stopped almost all work on their living quarters and the schedule that Ralph has set up for maintaining the rescue fire is not being followed.
Mentally, the best example to give would be the rock throwing incident between the littleun and Roger. The line between civilization and anarchy- good vs evil - is getting thinner. The old rules of Mr. Policeman and Misses Teacher are becoming fainter. Thus, the rule of "Don't throw rocks at people!" is barely remembered, but still there. As that rule and others that keep the inner beast at bay are forgotten, and as more time passes by on the island, beware, the rocks will start to strike the bodies.
You want the early signs only? Well, these start on the first page: the fact that the boys are stranded alone on the island, without adults. Almost as soon, you get the fact that they heard rumors of war, perhaps atomic. This is followed by the world seeming to turn upside down—Ralph standing on his head—and then by almost all the first details. (Things fall apart very quickly.) To list just a few of them, Ralph, Jack, and Simon follow a trail made by animals as they explore the island (following in the footsteps of animals). Ralph establishes the rule that only the boy holding the conch may speak—but immediately violates it. They start a fire to signal ships—but can't maintain group focus long enough, and it gets out of control, much as the entire situation and their less civilized drives will.
They possessed some good and bad qualities about them throughout their ordeal in the island. When they were left abandoned in the deserted island after the crashing of the airplane, Piggy, Simon, Ralph, the main protagonist and many other boys show elements of goodness in them. Ralph is "good" as he was really concerned about his clan's welfare and was really sociable with different kinds of people. What defines good? According to dictionary definition, good is:
(having desirable or positive qualities especially those suitable for a thing specified).
Piggy is good as he is a intelligent and witty boy, his "voice of reason" supported by his scientific approach to problems that help substained Ralph's leadership and control over the whole clan. Simon is always lending a helping hand to others and unafraid to stand up to any danger.
But, of course, they will ultimately fall victim to "sin" in their quest for survival, represented strongly by Jack and Roger. Something that is controlled by the force of reason, like fire is used to cook chicken or to keep themselves warm, but if it lands on other devious creatures, it could be a element for terror, destruction and mayhem. Everybody who was in the island was later on destroyed by Jack's evil and devious schemes and they could not withstand the evil influence pervading the entire island.