How can I apply critical work to my own writing?

As you progress in your study of English Literature, it will become more and more important to incorportate critical work into your own essays. Lots of students are afraid of plaigarism, but working with critics is most often more helpful than not; you just need to understand how you might go about building on their thoughts, rather than using them to replace your own.

A published critic is someone who really knows what they're talking about, but that doesn't mean you can't disagree with them. Examiners are far more impressed by a discussion than a simple regurgitation of critics' opinions, so if you decide to cite somebody else's work, make sure to challenge them, or at least add to what they've said. 

For example: Northrop Frye argues that Shakespeare's comedies are based on the Green World model - where for a time characters are transported to another place where mischief and magic rule.

Sure, this sounds clever - but ask yourself, is that actually entirely true? Or is it quite so simple? Some comedies don't appear to have a physical 'Green World' at all, but mischief still reigns (e.g. Much Ado About Nothing), while some are literally set in a forest (e.g. A Midsummer Night's Dream). Try and complicate what the critic has said, you don't have to disagree with them, but it pays to participate in a discussion.