How to quote multiple lines of verse inline
If I am using a quote that is only one line, I would not need a / between lines. But, when do I use a / - for free verse or blank verse? I'm a bit confused.
The divider is precisely to indicate the end of a line when it may not be obvious; so for unrhymed verse it is, if anything, more necessary. As an example, Shakespeare reminds us that "... set my teeth on edge/ Nothing so much as mincing poetry".
This assumes, of course, that you are making only a passing allusion. If the quotation is an important part of your argument, it's almost certainly worth blockquoting:
('Not men, or gods, or even booksellers/ Put up with mediocre verse'; I'm sorry I couldn't find an apposite English tag that starts in the middle of a line.)
In the MLA style, when quoting fewer than four lines (at which point, and thereafter, you ought to format it as a block quote instead) you place a "/" at the end of each line of verse. So, every five iambs (or so) for blank verse (which makes up the largest part of Shakespeare's works).
I'm having trouble thinking of anything in one of his plays that I would consider free verse. If you are referring to the small bits of prose he sometimes mixed in, you would not use the "/" at all. Simply format the quote like you would any other bit of prose. In other words, if there are no hard returns at the end of each line, don't include a line break "/" in the quote.
To sum up, for MLA, use the "/":