If you go to the board of studies website and look at the sylabus stuff for art, they will have the marking criteria for your B.O.W.
The markers have to follow that when marking, its not really based on their own opinion, its like an english essay, if you dont have at least 4 quotes then you cant get a certain mark (just an example)
but, yeh, go to the board of studies for the marking criteria or you could ask your teacher if they have a copy, they probly would of mark your trial or progress for your b.o.w based on the marking criteria that the hsc examiners use.