What Qualities made for a good leader of the Tokugawa Shogunate:
Strength:
During the recent periods preceding the Tokugawa Shogunate, Japan had been governed by a series unstable, relatively brief shogunates, so when Tokugawa Ieyasu, the founder of the Tokugawa Shogunate, came into power, he immediately sought to ensure that the Tokugawa clan's rule would be secure. He achieved his goal by demonstrating the same, central characteristic that all Shoguns before and after him had and would continue to display: military strength. Shoguns ruled through military control, rather than diplomacy, and any shogun needed strength to maintain their rule, but this factor was especially key to Ieyasu, for since he did not inherit his rule, he had to seize control of the state himself in order to obtain it. Military strength played a key role in any shoguns rule, especially that of Ieyasu, who managed to establish a Shogunate stable enough to put an end to the disarray and turmoil that Japan had previously been gripped by, but strength alone was not enough to keep a shogunate running for as long as the Tokugawa clan's did.
Strictness:
Japan's shoguns had always had ways of suppressing the local daimyos, who were basically feudal lords, in order to keep them from revolting or creating excessive disunity within the state, however, it was the Tokugawa's third shogun, Tokugawa Iemitsu, who provided the final nuts and bolts to his clan's shogunate's stability when it came to these matters. Iemitsu exemplified another attribute key to successful shoguns: strictness. By enforcing very strict regulations over the daimyos' powers, such as requiring them to seek permission from he, the shogun, before marrying or fortifying their lands, Iemitsu kept the Tokugawa Shogunate stable and set an example for the shoguns to come, but that was not the only thing that he achieved.
Xenophobia:
Along with keeping the daimyos in line, Iemitsu was also the shogun who enforced the Tokugawa's ban on Christianity, as well as trade. His isolationist policies helped encapsulate Japan, keeping the Togukawa Shogunate safe from western influence and instability, and while it may have had a negative impact on Japan's development in the long run, this xenophobia was a common trait shared by many shoguns of the Tokugawa clan.