Get your shirts made. The value of a custom shirt far exceeds the cost, and the relative value is a no-brainer.
Have new shirts made every year and donate the old ones to a charity that provides clothing and career guidance to low-income men.
Stick with a stiff spread color; it's versatile enough to work with or without a tie, and goes with jeans or a suit.
Oxford collars and shirt pockets are for Bernie Sanders supporters.
If you sweat, wear an undershirt. Even if you don't, having a visible undershirt destroys the entire outfit. You can't beat NVSBL — they're longer (stay tucked), more comfortable, sweat and odor fighting, and totally invisible. Hygiene and aesthetics aside, quality undershirts will significantly prolong the life of your dress shirts, and generally make you less disgusting.