Some good advice from VO2!
In your base phase you will need to do some endurance type training. You may also want to analyse your ability and the demands of the event to identify where you are lacking and build this into the training. Don't neglect your weaknesses!
As the year progresses, increase the amount of 'event specific' training (i.e. high intensity) to add the 'icing to the cake'!
A common practice is to use four phases; preparation (base), precompetition, competition and recovery. These may be repeated once a year (i.e. single periodisation) or for riders with more than one goal they may be repeated a number of times (i.e. multiple periodisation). In each phase the training focus (i.e. endurance, etc.) is changed to build up to the targeted event.