This was one of the first questions I asked myself when embarking on the big jump from GCSE to A-level and the answer is by looking at the marking criteria. Unlike GCSE, the English Literature mark scheme is rigid and you will get no marks if you divert away from it - no matter how good your point! After all, this is how the examiners are going to be marking your essay, so it will be far more useful to know that mark scheme inside out before even embarking on writing.
Once you have mastered that, the next stage is planning which is essential in order to get a good grade. Split your points up into paragraphs ensuring that you include each Assessment Objective stated in the mark scheme. I often found it useful to use a grid to make it more visual. Once you have inserted the main points then you can delve into the detailed aspects of your essay - jam-pack your grid with quotes, reminders to link each paragraph, anything you might find useful. Once you are satisfied with your plan the actual writing of the essay should be a walk in the park - if it isn't then go back to your grid and adjust it - perhaps you added too much/too little information? Repeated practise of this technique is essential to getting a good grade in English A-level!