At the SC, as soon as you walk in the front door, you are faced with an important choice. There are 3 major paths open to you before you walk into the room and each will take you to a different possibility. In the old-time gaming world, we would look at "go left, go right, go back or go straight." Look around. The first choice you see may or may not be the best one.
You might need a little help from someone at the SC to get everything you need there. If you help someone get what they want, they might help you get what you want - or at least hook you up with someone who can.
In case you haven't figured it out, whenever the border around the scene is red, there will be hidden hotspot choices in the scene. No red border, no hidden hotspots. It is possible to have 2 or 3 visible choices and up to 1, 2, 3, 4 or more choices hidden around the scene. Some of those choices may not have any bearing on the path you are following but many will. If you think you are missing something, make certain you didn't miss an important choice. That one might be what you need.
Another general hint - Brad's mood and behavior matter as much as the various girls'. If you start him out as a cad, you might want to keep him acting that way and see where that takes you. If he is gentlemanly, that might be a good way to keep behaving. Flirtatious, seductive, business-like, aloof? Keep track of
who and what he is during each story path. They matter and will get you to different places in the story. Some will be good in various ways and some will be pretty bad.