It depends on the question. One suggestion is to do the art paper backwards. Star with the big essay in Section II then work your way backwards through Section I This way if you run out of time you only threaten a question worth 5 marks instead of an essay worth 25 marks.
Look at the question. Underline the key words. Start your essay with a punchy quote that sums up your answer. Use a key sentence to start each paragraph and limit what you write about. You can write enough for a book on some questions.
Remember to use lots of details like dates, country of origin, size etc that can be found besides pictures in Section I. One of my friends also used the pictures in Section I to help answer his question in Section II. He got an OK mark.
Write in the terms of the syllabus. Use lots of words from the syllabus. Teachers like that. Find the syllabus on the BOS site. I like that
www.aaart.tv site. Its got lots of stuff. I have used it all year