The biggest foundation of Charlemagne's success was very influenced by the power of his military strength. His military strength helped him overcome obstacles like battles and fights. Without his military power he probably
Pope Leo III
Charlemagne's power was greatly influenced by Pope Leo III. Pope Leo recognized him and asked him to help the Pope fight against invaders. After Pope Leo III was safe from the invaders he named Charlemagne the Emperor of the Roman People.
Aachen
One step that Charlemagne took to greatly improve his empire was to establish Aachen. In Aachen Charlemagne built a huge palace and a cathedral. Aachen was the capitol of Charlemagne's empire.
Empire Overseer
Charlemagne's empire was pretty big and could not be overseen by only him. Since he could not oversee it by himself he had to choose officials called counts to rule parts of the empire in his name.
Education
Charlemagne wanted his empire to have some sort of education. Charlemagne ordered churches and monasteries to start schools staffed by the educated monks and priests.
Religion
Charlemagne's empire was at first an empire with many mixed religions. As an emperor Charlemagne worked with the church to create a unified Christian Empire.