Use the Gold you earn throughout the game to conduct research on both war and civil technologies that will gain you advantageous boosts in the aforementioned divisions.
Remember however, that the research level is related to the building level so be sure to upgrade your Blacksmith and University so that you can continue to increase your research level unlocking a raft of cool technological advancements along the way.
This type of research is related to the city and resource technology (e.g. resource production rate) and is only available in the University
This type of research is exclusively related to military use and is only available at the Blacksmith.