Game UV unwrapping

I’m creating a game in which characters (male and female) will be able to equip armor as they acquire it. My plan for doing this, is to make changeable textures (all the same basic skin texture with various changes made for each armor) and then have different models which will also change if there is a part of the armor that is not ‘skin tight’.

First, is this a good way of approaching modeling/texturing?
Second, how should I go about unwrapping my model to optimize space and accuracy?