One thing my teacher said was to not get too worried if you don't understand the plot, the intricasies in the plot shows that this aspect of the film is not being valued as much as other things. Therefore don't try to remember all the plot, or try to understand it all - I don't and I don't plan to try either.
I don't think learning quotes is that important either, the whole thing with genre is that you need to learn to identify the conventions put into place, and anything new that has been added to the C.F. genre. Therefore try to pick out what conventions have been used. for example the characterisation of Marlowe is typical of that era - charming, cool, not quite always doing as the law says, blah blah blah. Another example, use of film noir - ie the shadows and such, to create a sense of confusion (which is another reason why the plot is so hard to understand).
These conventions reflect what the society at the time of composition were wanting.
Hmm....
