I think the main weakness of a Wood Elf army is their reliance on keeping their enemy at a distance for as long as possible. They need to maximise their missile capabilities to thin out the enemy ranks because they do not have great rank and file units. All their best big unit fighters are skirmishers (Dryads and Wardancers). Also the army is very lightly armoured.
I will therefore be trying to engage them in combat as quickly as possible so will need some cavalry.
(see Part II - Exposing the Wood Elf Weaknesses)