You always have to keep in mind these 2 words: "dotted line". Any time you see a solid line, it represents a side/plane that is directly visible to you from that angle that you are given, wether it be top, bottom, or end view. If you see a dotted line, then you automatically know that that side/plane is not directly visible to you, and is actually obscured by another plane/wall(?). Keeping this in mind, I would suggest you do as many of these as possible. there is no one explanation that will help you figure out how to do this or any other section of the pat. after doing them over and over, you will start seeing patterns, and realize that there are certain rules. I used crack that pat, the basic package where i had only 10 sets of tests. I practiced on those intermittently for 3 months, and then consistently for another 3 - like every day. you just start "seeing it" after a while.
Good Luck!!