If I were a ruler of a great empire today, I would be very careful in terms of leadership as my greatest ambition would be to reign and expand my kingdom as much as I could. I would be sure that even if something happens and I pass away my generation would be also powerful and as prosperous as I was and maintain the same continuity to their next generation as the Neo Assyrian expansion empires did. They considered themselves as a part of unbroken kings dating back to 1500 BC. Their expansion relied upon the ideology of regaining the Assyrian territory lost by their fore fathers. It was time of returning their territory and reestablishing a tribute and military presence all over the central empire. The basis of success as an empire is going to step ahead of your fathers and leaving a legacy for your successors to do more than you did.
Though brutality is inhuman, I would apply it to my rebels as Assyrian Empire did. The only difference would be that I would be applying it to my enemy but not to my people as Assyrians rulers did. They were very brutal and imposed heavy compulsory taxes that would cost a civilian a life if found not cooperating. I would in turn use this brutality against my enemies and rebels. A chance would not be given to any sort of revolutions or attacks from other empires. I would also emulate the Roman Empire in terms of military set up. They were vast in numbers and their training was one of the best ones that had ever existed in the history of empires.
The strength of any empire relies basically on the military set up. The stronger the military was, the more stable the empire was. This fact made Roman Empire very strong and helped to conquer a very large territory. They would win almost all the battles, looting their wealth, taking them as slaves, and ruling their territory. This also worked well in the Troy Empire which was relatively small, but any other empire could not manage to beat and overcome them. Only the Greek Empire managed to take them down and burned the whole city of Troy having done several attempts that failed. The reason why this empire overthrown the Troy was that Greeks came in numbers, almost fifty thousand soldiers fought against the Troy soldiers. This gives us a significance of the superiority of a strong military.
Again, I would also consider democracy but in moderation just like the Athens Empire did. The greatest legacy of the 20th century was emergence of democracy especially within the Athens Empire as a universal value. This democratic value is now commonly applied as a fundamental moral requirement in state governance and other institutions. However, I would moderate this in my empire so that it would not be over exploited by some opportunistic individuals. Democracy application was one of the reasons that led to the fall of the Athens Empire. For instance, I cannot give my people a chance to choose whether to be soldiers or not since many of them would be unwilling to join the army. There are certain issues that if left for democracy to prevail, will bring you to the ground. Comparing the Athens and Assyrian Empires, I choose the Assyrian one, a democratic empire is more likely to fall rather than a brutal one.
I would also find smaller territories and amalgamate with them giving them inferior powers to strengthen my empire. Creating good rapport among other foreign empires is important as it improves security in terms of trade, militia alliance, and political stability. Peace and treaties are also a method of evading defeat in case my enemy is stronger than me.