Yup. well....Angie's body type recommendations (and others that I found) were the start. I really had no clue what actually looked good on me and I am still learning the fine points as I go.
I think the first lightbulb moment for me was when I cut my hair. I had mostly worn my hair short (most of my life) but just prior to joining YLF had grown it out to an almost shoulder length, a bit longer than your current hair. And I was really having a hard time getting dressed then.
Anyway. Angie told me to cut my hair and all of a sudden the tops that had seemed to work with longer hair looked hideous on me! Meanwhile, my old favourites (like turtlenecks) finally looked great again.
It changed the proportions entirely. I needed to figure it out.
so...."structure in shoulder or neckline.." --- Angie talks about this a bit. She is quite rigorous for herself in never wearing a shirt that exposes the shoulder-neck point (where the shoulder joins the neck) -- which is sort of the OPPOSITE of what will work for you.
I'm not quite as strict on this for myself (my neck is not quite as long and slender as hers and my head is longer relative to my height than hers, so the proportions are a bit different).
But I face similar issues. Long neck, short hair, small bust, generally small frame...if I expose too much chest it can: 1). look bony and yuck; 2). show how little there is to expose, LOL; 3). slide around in a very annoying way; 4). mess up my overall proportions, making me look sort of bobble headed. Or even more short-legged than I actually am, because the top portion will look so LONG by comparison. Like Alice in Wonderland when her neck stretches out, you know?
Well, except she has the long hair to help disguise the problem.
ETA: my age also plays a role here. In my younger years, even if I was relatively slim, I could expose more chest area without it looking "bony." Now, not so much. Partly this is related to weight changes due to exercise, etc. and partly weight distribution changes purely due to age. Alas. Anyway. You get the idea.
The terminology might be a bit confusing because Angie often uses the word "structure" when she's talking about exposing skin and here I am talking about not exposing skin. But as I understand it, "structure" means highlighting the frame, i.e. the shape of the body, the bone structure. So for different body types, different cuts will provide structure. And the cut that is just too loosey-goosey for me (slides around or overwhelms me, thereby hiding me) will be excellent at providing structure for a person with a different body type.
Returning to you for a moment, you will wear open necked styles beautifully. (Like those new tunics). They won't swamp and muffle you. They will show you and allow you to shine.
Theoretically, you might be able to wear cutaway collarless coats and jackets. (See the Theory Lanai for an example). Or -- if you wanted to belt, you could wear a wrap dress. And you can wear the very drapey styles like some of EF's cardigans and tops. Fluid with open necklines.
Whereas I will do best with a high collar (turtleneck, shirt collar, mandarin, or crew). If I do wear a V neck, it needs to be quite narrow. I can wear a boat neck but it should not dip too low in front. Set in sleeves are often best, although I can get away with raglan sleeves if the neckline is a good one. And so on.
How I figured it out? I tried stuff on and took pictures. In fitting rooms. In my own house (with tags still on so I could return). I paid attention to what I kept on reaching for and what I ignored. I studied the photos as dispassionately as I could. Sad that some things just wouldn't work on me. Glad that others made me feel more like myself. And so it goes. I'm working through the same process now with pattern and with degrees of contrast in outfits. Learning as I go.