Keep a record of everything. It'll come in handy.
It's amazing how quickly memories get mixed up. And paper gets shredded. And loyalties change.
You need to keep a record of every personal occurrence in the workplace. Congratulatory emails. Celebratory performance appraisals. Unreasonable asides. Snide remarks. Whatever.
It's not for legalistic purposes. It's to make sure your own thoughts remain clear, your conversations are genuine and if push does (hopefully not, but you never know) come to shove, you have credibility in stating your point of view.
Ranting and raving about how everything is unfair is useful with Friday evening alchohol. Remembering that your recent launch was appreciated with an award on a very specific day, or you sent an email expressing concerns with a situation to a particular distribution list is useful with Monday morning coffee.
I downloaded Awesome Notes (http://www.bridworks.com/index.html) and Toodledo (http://www.toodledo.com/) apps on my phone and got in the habit of keying in bullet points reminder of the day on the long and enthralling tube rides home. That turned out more useful than the hours I had previously spent killing our pointlessly suicidal, irrelevantly pissed off feathered friends.
Awesome notes has nice graphics and good colours. Toodledo has the advantage of syncing across devices and is easy, even if ugly. (As an aside, I should mention that neither of them are paying me for this endorsement, more's the pity. In fact no one has ever paid me to endorse anything but that's a whole different story)
So, download some apps, and keep your notes current. Hopefully you'll never need to refer to them again.