Focus less on learning the content and more on practice responses. With modern, a great memorised knowledge of the content is NOT essential for success. As my modern teacher used to tell us, modern isnt about what you know, its about how you adapt your knowledge for the purposes of the exam. At the end of the day, an essay question isnt going to ask "Explain what happened in the Russian campaign of WW2". It is more likely going to ask, "Evaluate the impact which the Russian front had on the outcome of the War". So focus on knowing the issues, as opposed to memorising dates and minute details like that which arent really going to help your essay.
Also, you should focus on doing practice responses on generic questions. For instance, with Germany I did a practice essay on "Analyse the reasons behind the collapse of the Weimar republic". I did this essay as practice because it is common to see some type of question on this issue in the exam (last year it was the armies role in the collapse of Weimar).