biology

Only constant practice can help. Before attempting to draw any figure, understand the theory of the figure. Once that is clear, try drawing the diagram. You may not be able to draw it perfectly at first, but constant practice will help in achieving perfection.  There is no other way to remember the diagrams, except through constant and regular practice

Also you can use the following link

http://topperlearning.com/toppernews.php?event=archdet&newsid=17  and classroom cracker on home page of topperlearning has important diagrams.