Shi Huangdi, the first Qin emperor, started the building of the Great Wall of China. This helped unify China as it defended them from foreign invaders and broke down the walls between neighboring villages.
Shi Huangdi also saw the wisdom of unifying China's currency. This improved the economy, trade, and unity of the empire.
One legal system was promoted throughout China, legalism. It was harsh on criminals but it helped reduce crime which created a safer atmosphere.
Noble families were moved to the capital to be observed by the emperor's spies. This was so rebellions would not occur due to imbalances in power.
Shi Huangdi attempted to unify China by censoring thought and destroying all the documents that disagreed with his policies. This, unfortunately, did not work, and it was one of the things that led to the dynasty's downfall.