Visual Studio is a capricious product, and its "Solution" subsystem is especially capricious. When you look at what options are available you might think you have a great degree of freedom to structure things the way you want, but as you will inevitably (and painfully) find out later, many things have to be done in precisely one, entirely undocumented way, or else there will be pain of the worst kind: Visual Studio will malfunction either without any error message, or with error messages that are completely unhelpful for locating and fixing the problem.
Here is a list of things I have (painfully) found out over the years.
