Shall I say, I have gone at dusk through narrow streets And watched the smoke that rises from the pipes Of lonely men in shirt-sleeves, leaning out of windows?…
Here he wonders how to "begin" to talk about that difficult subject. And the difficult subject is…himself! Oh, brother.
This is the story of his "days and ways" from line 60, and it begins "I have gone at dusk through narrow streets."
But, of course, we know that already. He’s basically taking us back to the beginning of the poem. The most interesting new detail he has to offer us is that he saw "lonely men" smoking pipes out of their windows.
Some people bring the party with them wherever they go; Prufrock brings the loneliness with him.