I’m a great believer in inputting something once and then using it multiple times – I’m a database girl at heart – and Mendeley suits the way I think.
To begin with, I cheated somewhat and imported a bibtex file that I had exported from the software I use to catalogue my books. That saved an awful lot of typing. But for new books I’ve bought, I input them manually. You can also import from other reference managers, but I haven’t tried that.
I mostly use the desktop software (on Windows and my Mac) and creating new references couldn’t be easier. You select the type of thing you wish to reference and it presents the appropriate fields. Papers are even easier, as you can import the PDF and it has a stab at identifying it, using Google Scholar. Bliss.
My normal workflow is to create a folder for the essay or topic I’m researching and then drag likely-looking candidates into it. This makes it quicker to locate the reference later and I can remove stuff and add stuff as I go.

My working setup: the folders on the left allow me to organise documents I want to use for each essay
Once I have my document recorded, I can then input notes against it directly, using the Notes tab. These notes are synced and available on all my computers and even on my iPhone.
I let Mendeley save my PDFs with the record, so I also have access to these documents on all my computers and phone. You might not need this, and you only get a certain amount of storage for free, but it suits the haphazard way I work 🙂
You can set the citation style in Mendeley and get it to display the list of documents as either a table or just the list of citations. I normally choose this, as I can just copy and paste the citation into an email really easily with it set like this.
Now for the exciting bit: actually using all this data. I’ve found that the Openoffice and Word plugins seem to store things differently, so I only work in one or the other on a single document.
Whatever flavour you choose, you need to install the appropriate plugin from within Mendeley itself. This should give you options in your word processor for interacting with the Mendeley data. In the case of Word 2010, you get an extra block of gubbins on the ‘References’ tab.
The first thing to do is set your citation style, as obviously there is more than one. We use Harvard, so select that. Sometimes I’ve noticed that it ‘forgets’, but don’t worry, it’s just a formatting rule so your citations will update to the correct format if you change halfway through, so is fine to just check this at the end.
When you’ve written something you need to provide a citation for, simply go to the Mendeley tab in Word and insert the citation. This will bring up a dialogue box to allow you to navigate to the required reference. You can either use the search to locate it, or go to Mendeley itself to locate the required document. See where the folder thing comes in handy? If you need to add a page number to the citation, you can edit it without destroying the link. Click okay on the warning if it grumbles about changing it.
If you use Mendeley itself to browse to the reference, you will get a new ‘sent citation to word processor’ button appear in Mendeley, which is what you click to select the thing you want to send.
Inserting your bibliography is dead easy: put your cursor where you want it to appear and click insert bibliography. It will magically update as you add more references.
So, it’s all very simple, but I do find it helps me organise myself and put the citations in as I go. Having a folder full of documents I intend to refer to is also a good double-check to see you haven’t missed out any citations in your essay!
One more thing: you can set Mendeley to keep watch on a particular folder on your computer, and import anything you put in there. This is fab as it allows you to trawl Google Scholar for likely papers, download them to this folder and Mendeley will try and import them for you. It doesn’t always parse the document correctly, but generally it gets it mostly right, and any that it knows it got wrong can be found in the ‘needs review’ section waiting for you to fix.