Maintaining a high combo is the single most important factor for achieving 'A+' grades. The combo meter has a timer; if you don't kill an enemy within a few seconds, it breaks. To keep the combo going, you need to move quickly and efficiently between kills. Plan your route through a floor to minimize downtime between engagements. If you're running low on enemies in one area, quickly move to the next. Executions extend the combo timer slightly, so use them when safe. The 'Tony' mask is excellent for combo management due to its instant lethal punches. Don't be afraid to restart a floor if your combo breaks early; it's often more efficient than trying to salvage a low-scoring run.
