How did Napoleon lead his army on the battlefield?
Napoleon ranked high in motivating his army. After his death, autopsies showed napoleon was injured far more often than anyone suspected. This at least shows that he was often on the front line with his troops.
While he was still training as artillerymen, he was annoyed by the officers who trained the nobility. They would command the army, but they didn't know what the soldier at the bottom of the chain had to endure. He planned to write a letter of complaint to the War Department. Fortunately, his teacher prevented Napoleon from sending the letter, otherwise we might never hear from him again.
During the siege of Toulon, he was given his first command. He immediately noticed that the artillery position was not good, the troops were under-equipped, undersupplyed, demoralized, and poorly led. Napoleon quickly reorganized his entire army, repositioned the artillery, and gave them all the inspiring names, such as "The Battery of the Fearless Man" and so on... This gives men a sudden sense of self-esteem. For them, it was fresh for them to see their commander sitting among them, eating the same food surrounded by his soldiers, to see him stain his boots and sleep in the same mud as his men. He spoke their language and shared their grief. He was a leader sitting on a mountain. He inspected the lines and inspired the troops. Napoleon wanted to be seen by his men.
During the Italian campaign, he again took over a poorly equipped, low-paid army on the brink of rebellion. He again lined up his troops and won a victorious battle. During the Battle of Alcor, he wrapped a French flag around his sword and planned to lead his troops across the bridge. However, he did not reach the bridge and was trapped in a muddy ditch and rescued by his staff.
The first time he was unable to maintain high morale was during the Egyptian campaign. More specifically, as he continued to advance throughout Syria. His speech and commitments could no longer provoke the troops who were getting farther and farther away from home than any of his former troops.
When he inspected his troops, he would be informed of some of the soldiers' achievements in battle. He would talk to the soldiers, praise him for what he had done, and pin a medal to his vest. This was not seen at the time. The soldiers felt that their leaders understood them, cared for them, and shared their hardships. His prestige rose to a huge proportion.
However, Napoleon was not a god. Many have noticed that his command has changed as he ages and looks. Some historians believe that Napoleon was tired of military action and was increasingly unable to endure the hardships of weeks of marching and fighting.
The absolute turning point was the Battle of Russia in 1812. All surviving testimonies suggest that something inside Napoleon was destroyed and never returned. (This was the case for many survivors of that terrible movement.) He had become fat, his eyes were no longer on fire, he would fall asleep, and the enthusiasm that had inspired his troops was no longer there.
He remained a tactical planner, and he proved it in the 1814 campaign, which is often regarded as his best campaign.
During the Time of Waterloo, Napoleon was no longer the commander he had been. As the army marched to their positions on the battlefield, some testified that Napoleon would fall asleep in a chair while his men shouted "Long live the Emperor." His attacks were straightforward and not really inspired. His age and hemorrhoids made it impossible for him to examine his troops and visit the front lines. His presence no longer has the expected effect on men. He had to leave the battlefield to rest. By the time he returned, Ney had thrown the entire French cavalry into a suicidal charge against English Square. Napoleon saw this, cursed Ney, and then... Nothing was done. This would have been unthinkable a few years ago.
Edit: Napoleon's departure from the battlefield at Waterloo appears to be propaganda after Napoleon's departure. While I did read several books confirming his departure from the field, there is not enough evidence to support this. But my point still holds. It is unthinkable that with or without Napoleon present, he will not try to stop Ney's attack.
I hope this is enough to answer your question.