So one problem I am always facing is "Where to put the vanishing points?"
I feel like this is something, I don't read a lot about. Maybe I just haven't found the right source. It is one thing to know how to construct a grid. But another to use the grid in a way that helps to communicate visually with the viewer in the right way.
So I think that there usually is one "main vanishing" point. It is the one most objects in the scene adhere to. This main vanishing point informs all the other ones and should be placed carefully.
Lets look at a pro and see how he does it.
So in this example, one vanishing point is on the focal point!
Please note, that there is more than one vanishing point in the above image. The second one is far out of the picture-plane to the right. Can you see it? By putting one inside the picture-plane, the other one has to be outside. Why? Because of another very importing topic of perspective, which is "lenses" or "lense-width". But I will discuss this another day.
Now more examples. See if you can find the main vanishing point.
I hope it helps :)