if you seriously do alot of problems, you start to notice alot of things when scanning TFE images. top view, how many different planes? then look at front view, what did those planes represent, does one piece stick out? is that piece a cylinder on another view? is it higher or lower? etc. just build a 3D image with the pieces you can put together! also many times similar answers will drastically vary in solid/dotted lines. do some problems and review them! good luck