I've learned to make my perfectionism work to my advantage. I have become proficient at meeting deadlines, and with my attention to detail, I know my work is accurate.
As an undergrad, I used to leave assignments until the last minute, but with the workload of graduate school, I learned to schedule my time very effectively.
I used to like to work on one project to it's completion before starting on another, but I've learned to balance work on several projects simultaneously, and I think it allows me to be more creative and effective.