The answer to where they do lie is much harder than the answer to where they don't lie. Bradbury doesn't just come right out and say it.
After the part you quote, Faber does say that Montag has to do some of his own saving. In other words, he has to rely on himself.
But overall, in this passage (going from "your" part to the place where Montag leaves Faber's place), the idea is that the answers lie in having lots of people trying to do little things. He says that they have to start small and work their way up.
However, he also says that society needs to be melted down and restarted. At the end of the book, that is exactly what seems to (possibly) be happening.