Preparation is the most important thing to consider when starting a new exercise.  Mountaineering, even though some may consider that it is not an exercise, it does require a high level of fitness.  It also requires that the correct equipment for any eventuality is carried.  One of the important pieces of equipment that I consider is an altimeter watch.  I have owned a Suunto altimeter watch for years and have never been let down.  As long as it is regularly calibrated it will give you accurate results about your attitude.  The newest altimeter watches that they have released are the Suunto Core and Suunto Lumi range.  The Suunto Cores come in a large number of different colours and replacement straps can be bought from them all if you decide to change the colour.