To use quotations effectively, you will need to put a lot of work into preparation and follow-up, so it is not a good idea to plan to fill up your essay by a lot of long quotations without much material by you in between them. Using quotations in this way is essentially a writer-orientated mode of writing which won't meet the expectations for a university essay.
Referencing sources, which you are expected to do, is not the same thing as quoting them. You only need to quote directly from a text if the actual words the writer has used are important, and you're going to discuss what they mean. Summarising or paraphrasing secondary literature by using indirect quotation accompanied by proper referencing (eg "J Hillis Miller argues that..." plus footnote with page reference) is often a better idea than quoting directly, since by doing this you show that you have understood what the writer you are referring to said, whereas any fool can copy out a quotation.
Summary and paraphrase are better, because direct quotation threatens the reader's experience of coherence in your essay by introducing material which won't obviously relate to the way you've been defining the problem posed by the essay. Although the relevance of a quotation may seem obvious to you, it won't be obvious to a reader unless you provide cues through framing the quotation, perhaps by an introductory sentence or even paragraph which explains the general relevance of the quotation, and following the quotation with some commentary which sets out its relevance in detail.
The longer the direct quotation you use, the longer your introduction to it and following commentary will have to be in order to maintain the reader's sense of coherence - you should aim to make your commentary on the quote about three times as long as the quote itself. You can integrate very short quotations (ie a word or a key phrase) into the grammatical structure of your own sentence, as embedded quotations, but lengthier quotations (ie anything over a sentence) will need to be presented as a separate paragraph, or block quotation. If you give a passage of poetry in a block quotation, it should be set out as it is printed, since the use of the slash character (/) to indicate line breaks is only acceptable in embedded quotations.