| Quote #1
His clothes were a trifle outgrown and the tan velvet on the collar of his open overcoat was frayed and worn; but for all that there was something of the dandy about him, and he wore an opal pin in his neatly knotted black four-in-hand, and a red carnation in his buttonhole. (1.1)
If you can read this without a single tear in your eye, congratulations on your cold, dead heart. The neatly tied tie, opal pin, and carnation—details that show Paul cares a lot about his appearance—contrast with the fact that his clothes are worn-out and too small. Paul's father probably has money to buy Paul better clothes (we learn that he's not poor), but obviously doesn't think it's a priority.
| Quote #2
[H]is father, on principle, did not like to hear requests for money, whether much or little. […] He was not a poor man, but he had a worthy ambition to come up in the world. His only reason for allowing Paul to usher was, that he thought a boy ought to be earning a little. (1.26)
Look, something Paul and his father can bond over: money. Paul's father loves money just as much as Paul does, but for practical reasons.
| Quote #3
He spent upward of two hours there, buying with endless reconsidering and great care. His new street suit he put on in the fitting-room; the frock-coat and dress-clothes he had bundled into the cab with his linen. Then he drove to a hatter's and a shoe house. His next errand was at Tiffany's, where he selected his silver and a new scarf-pin. (2.39)
This is like the millionaire's edition of What Not to Wear. Out with the too-small, faded clothes, and in with the frock coat and silk boxers.