What are the most effective ways in studying for an unseen extract (Paper 1)

The first thing you would want to do is memorise definitions of essential literary terms (e.g.: metaphors, allegory, etc.) and make sure you are confident with those techniques specific to poetry and prose that should always be considered (e.g.: form and sound in poetry, voice and perspective in prose). For me, the best way to memorise these definitions is with the website Quizlet.com - a site that creates flashcards and provides enjoyable games to keep the student focused and entertained, but also effectively remembering the definitions.
Another thing to do is to read examples of Unseen Papers and then practice annotating the texts. If you've run out of papers to do, you can always get shorter extracts from any novels, short stories or poems. With past papers, write practice thesis statements focusing on the driving force behind the text. You, very unlikely, would not know the source of the text, so your analysis of the extract would have to based on what is provided in the text. Remember, that a reader response approach is important - in other words, how do you as an individual approach, read and analyse this text.