http://wiki.polycount.com/wiki/Topology#Principles_of_Topology Theory and examples for in-game models, vs. other kinds of models. http://wiki.polycount.com/wiki/Texture_Baking#Baking_Workflow Workflow for in-game models. Explains lots of the issues you'll run into for your model.
Trim sheets and multitexturing. http://wiki.polycount.com/wiki/MultiTexture But before doing that, I would look carefully at your topology. You have a lot of edge loops that do nothing for silhouette. Edge loops are needed for subdivision surface modeling, but not for real-time modeling. Two different types of topology.