On A Suitable Wardrobe Will talks about shirt fit. This is a topic I have addressed before and I feel it is an important topic, so I will keep addressing it. Will says:
Only a bit of a shirt shows at your wrists and below your neck, which is why the collar is the most important part of a shirt. Consider poor Stanley Tucci here, unbecomingly costumed for his role in The Devil Wears Prada. The fit of his collar is classic, with what appears to be just enough room to insert a couple of fingers between shirt and neck and about a half inch of shirt above the back of his jacket. But the proportion is off - the points of his collar are too long for his head.
So... what kind of collar should you wear? You should wear one that fits your face and body type.
First of all - In my opinion button-downs are only ok if you are going for that lower-middle-management zombie wage slave look, but other than that there is a world of collars waiting for you.
My collar of choice is the french collar, 1.5" back and 2.75" to the tips (See
KJ Beckett bespoke for a great set of images and measurements) This style fits my face and is classy looking yet when the top button is left open I just look like a nice relaxed "clean cut" guy. This style also has a wide enough spread for me to tie a windsor knot or a four-in-hand.
Find your collar style and you will be well on your way.
Image of Stanley Tucci from
out.com-TSG