Think positive and you'll get to the top.
Keep drinking and snacking on summit day - It was easy to forget to do this and my water bottle froze. I was jealous of the camelback with insulated tubing. Even a neoprene bottle cover would have made a big difference.
Hire the Exodus sleeping mats - You don't need to worry about carrying them and they looked so much more comfortable than anything you could buy.
Bring a nail brush - The grey volcanic ash gets everywhere.
Bring US dollars - Small and big denominations. Credit cards were only accepted at the airport. Bring more than you think as tipping the guides and porters becomes quite an emotional event and you don't want to be short when this happens.
Bring walking poles x2 - Turns out that they are not just for "old" people ;) They stayed in my bag for the first 4 days, but they were a life saver when skiing the scree on the way down.