I know a bit about Shakespeare, but how can I talk about his work without sounding boring?

Think about which of his plays you've read. If you're going to talk about him confidently and substantially, you should have at least three up your sleeve. The tutors will be looking for a unique and nuanced interest here, as he is arguably the most famous writer in all of English literature. If you haven't already therefore, read some his more obscure, lesser known works, perhaps alongside a filmed adaptation. I did this with his First Tetralogy sequence, watching the 1978 BBC versions as I progressed through the plays. This means avoiding the obvious choices like Macbeth, Hamlet, Twelth Night, A Midsummer Night's Dream, Much Ado About Nothing, etc. Most of his history plays tend to be overlooked, as do some of his tragedies, like Coriolanus.

Try to work out what it is that interests you specifically about the plays you read/watch. I appreciate this is a difficult question to address directly, so a good way of going about it is to simply note down as you read/watch any moments or lines you especially enjoy. For me, it was as basic as jotting down things like "Really cool line from the Duke of York in Scene Three: 'Did you think me so unnatural?'" The next stage is to try and find linking themes between the things that impress you in the play. Shakespeare is a monumentally complex playwright with a vast array of works and the tutors won't be expecting total expertise, but you can mask plenty of holes in your knowledge with a fundamental enthusiasm for his character development, word-play or the structuring of his narratives. By registering the Duke of York's use of the word "unnatural", for example, I was able to make a broader point in my interview about the importance of fealty between fathers and sons in Shakespeare.