The biggest problem with climbing Everest is obviously the altitude and the sometimes deadly effects it can have on you. There is no knowing how it will effect any one person at any given time. The only thing you can do to minimise problems is to acclimatise slowly and keep your body in good shape by drinking plenty of fluids and resting often.
Although its not the Himalayas the Alps have a few mountains that have helped me pre-acclimatisation, and living 2 minutes walk from the Aiguille du Midi cable car in Chamonix has also given me easy access to the top station at 3800m and the lower slopes of Mt Blanc.
From 3800m you can easily make the summit of Mont Blanc du Tacul (4250m) in a few hours. In the last few weeks I've done this 3 times and since I got to Chamonix 3 months ago I've been to 3000m 55 times including 45 times at 3800m or more!
With only 12 hours at sea level between leaving France and going to Nepal (via London), I'm sure I will be able to stay acclimatised and reap the benefits on the trek into Everest Base Camp. Not having to struggle with altitude on the way to EBC will surely help me in the long run during the 2 months expedition to the top of the world![gallery link="file"]