sorry i cant be more specific... you knwo trials coming up and all. but what i think you want is this:
Sulla was a great general. He used faithful troops as a popular general to meet his ends.
One of these ends was the first march on Rome to quell the anarchy resulting from Sulpicius Rufus appointing Marius to the Mithridatic command. (and obviously he was somewhat peeved at the tribune).
His legacy is the precedent he set by marching on his home land for a personal political agenda. This precedent was repeated by Lepidus in a 'counter-revolution' (Scullard) even before the death of Sulla and was to be attempted later by Cataline and the threat of it was constantly there with Pompey who used the fear of a political purge to obtain many special commands. Eventually this precedent was taken by Caesar with his march on Rome.
Sulla also left a legacy, again by fear, with proscriptions in order to fill the coffers of Rome - see Augustus
Another thing you should note is through his political purge he recognised the potential of the equites and enrolled them in his senate. Note: HIS senate consisted of strong willed optimates... at least those left from Marius' vengeful purge of the city in 87. He set up a obfuscation reactionary body that was to frustrate popular politics until 70.
Also his attempts to squeeze life back into the dying republic neglected to include the talents of the newly enfranchised. Althought he recognised their position across all voting tribes he did not enroll them in the senate nor did he take into account the provincials.
He himself was pressured into rewarding Pompey with the title of MAgnus and a triumph before he was even a senator and left his restructuring of the republic wide open to attack on his resignation.
Finally he set an expectation of temporary autocracy. When Pompey became sole consul in 52 (he was given the position to avoid creating a dictator and keep him under senatorial control) he was expected to quell the rioting of Rome. More significant is when Caesar became dictator the senate expected him to restore the republic as Sulla had. His refusal and later position of dictator perpetual cemented his permanence as autocrat and caused his assasination.
so in summary i would say Sulla's greatest legacy would be the precedents he set: marching on Rome for personal reasons and actions as an autocrat.
please check the sources yourself as this is my interpretation, not yours. You will need to back up conclusions made with sources from the text, something which i have not done here. In order to write a good response i would look at both cassius dio and Plutarch and a modern source interpreting the events at greater distance.
hope this helps