How can I reach the top marks in the longer questions of the written exam?

This is your chance to show off. This is the point in the written exam where examiners are looking to descriminate between the A* and the B candidates. You want to show them (or at least make them think) that you've really mastered the tenses and feel at ease writing in Spanish. The easist way to do this is start off simple, and work your way through to the most complex tenses by the end of your piece. So work through from the present, preterite, imperfect, future, and then conditional and hypothetical tenses. It would also be good to use one or two idioms to show you are really at ease with the language! 

Remember not to go over the word limit! They specifically say that they won't read beyond this point, and you dont want them to miss your best bits!