By revising a list of sophisticated words to use, it ensures that marks are maximised for expression in the exam. I wouldn't personally have too many for each genre of writing. 8-10 words or phrases is more than enough. For Literature these are the kinds of words I would encourage students to use, in order to demonstrate sophistication:
Demonstrate, subtly, cleverly, profoundly, conveys, enlightens, emphasises, depicts, evokes, portray, embodies or compelling.
Another tip to give students when revising, is to make sure that they watch any set poems on YouTube. YouTube is a fantastic tool to use as very often there are some clips of the set poems that are read out. On these clips there are often visual images to help understand the poems and also teachers explaining the key themes of the poems.
Lastly, I always recommend students of mine to read broadsheet newspapers. Often within these papers, if articles about politics are put to one side, there are really fantastic articles about interesting issues/subjects. The wonderful thing about reading a broadsheet newspaper is that this then provides students with all of the techniques that they themselves have to use (so these articles are a fantastic example of the kind of thing that students themselves need to create). In addition to this, students are provided with impressive vocabulary, sentence structures and tone usage - all things that they get awarded marks for in the exam.