I don’t think you need to notice it, but shirts are a vital element to modern male outfits (whether he seduces women or not). Once you pass the 20 year-old mark, you can not look serious wearing exclusively T-shirts.
Shirts, The Cuts
If there’s one word that you should keep in mind regarding your shirt, it should be this one: hanged. A hanged shirt is a shirt that follows all your body’s curves. When inserted in pants, a shirt should not float. Note that if you are a little strong (meaning that you have a few curves), you should prefer straight shirts.
The ideal would be that you’re thin, and you can question yourself regarding this.
Shirts : Collars
People who offer you tailored shirts should offer you about a dozen collars, each with very specific usage. Note that collars are possible, but not for every occasion. For a shirt that you will wear to work, you should prefer collars with tightened edges (classical collars, Italian collars, and British collars).