How do I effectively use critical sources in essays?

Using secondary critical sources in your essays can be intimidating but here are three ways you can apply it effectively:
1.To bolster your own argument - This is possibly the easiest way to utilize a critical source and is an excellent way of lending your argument some credibility. To do this you simply have to set up a point you are trying to make and then pop in a quote or paraphrased idea from a critic and address how this relates to your argument. Use this technique for: Criticism about elements of the text (be it a specific quote, a theme, a character, literary device or so on), the author's literary techniques and style, etc.
2.To offer an alternative interpretation of the text - Demonstrating your understanding of other interpretations of the text at the same time as using secondary sources is a brilliant way to earn a tonne of marks in one lump, especially in exams when your time is limited. BUT you have to remember to do this in a way which aids your essay. What you shouldn't be doing is presenting the critic's idea and your own on equal terms in a kind of 'on one hand... on the other hand' format. You need to be able to offer your argument as a better alternative to that of the secondary source. For example: Critics such as Sandra Gilbert in “The mad woman in the attic” have suggested that the character of Bertha in Charlotte Bronte's Jane Eyre functions as a manifestation of Jane's repressed self. However, I argue that Bertha functions as a representation of Rochester's dark past...
3.To say something which you don't quite have the authority to say - This means theory, historical evidence, anything that would be mere assertion if you just said it without evidence to back it up. This kind of stuff is useful to illuminate your argument in any way; it would be difficult and ineffective to discuss psychoanalysis without referencing theory from Freud (or similar) to set it up.
Now, the MAIN thing to remember when using secondary sources of any kind is not to stick one in and then carry on with your argument like it never happened. You have to ENGAGE with it. This means potentially unpacking your quote (i.e. explaining what it actually saying), relating it back to primary evidence from your text, and ultimately tying it together with your argument. Otherwise, what's the point?
Here's a tip:Make summaries - Reading long critical texts can get confusing and overwhelming, so a really useful thing I often do when it comes to secondary sources is making summaries of whatever the source says so that I have an easily digestible reminder of what's happening. This could just be a couple of sentences in your own words to sum up the overarching argument, and then maybe even a couple of sub-sentences to explain the different elements of this argument. If you have trouble pinning this kind of thing down, just look in the conclusion!