Well, it's true that one of a "must-haves" for a perfect capsule wardrobe is at least one stylish white shirt! You are very bright in your conclusion to pull up good wardrobe with a help of modern adviser: glossy magazines, fashion bloggers. I swear - you would make it! And perfectly!!
From our side , we would love to help you in every question towards your final results in it.
Me, i always tell my clients, that you should invest in your wardrobe with every purchase. All things should be taken to live with you not for 1 season.
And best option is to mix and match clothes between themselves.
So, perfect white shirt - is an investment!! Why? You can use it differently and every day: for daily affairs, for a bussiness workstyle, for some events/occasions or even for leisure time with your family or friends. You can perfectly match it to every style, wearing with jeans, mini skirts, classic stuff (pants, pencil-skirts etc)...
Investment piece doesn't depend on a price at all. I found hundred times great shirts at our beloved mass-market brands
First of all - quality! Good cotton quality. I recommend not very sheer one and with a bit "sliding" fabric.
It shouldn't ressemble a rag. And try to catch a proper shade - it should be really cooling white!! Snowing white....without yellowish, vanile shades.
After the quality, secondly, i advice to find a shirt with some elements! Interesting pocket, buttons, sleeves -not just a simple buttoned white shirt.
It could be a lace one! Or with small print somewhere: breast pocket, collar..
Unusual cope: with ruffles, for example. Let's say, a bit "difficult" shirt.
Here are some visual examples for my explanations: