The 3 main qualities you want to quickly identify in the ideal candidate are: Action Taken, Reliability and Skill Level. *These are in order of importance*

Action Taken - this can be discerned in the initial testing period. I'd rather have someone give me an example of how they screwed up rather than have done nothing waiting for directions. So give people liberty to take action, even if the end result isn't quite what you expected because with outsourced labour, you'll both be working on different schedules and you don't want them waiting for you to come online to fix a little problem or give more direction.

Reliability - Monitor your new employees during their test period. Again, tools like Time Doctor or Basecamp can indicate how much of the workload is being accomplished.

Skill Level - this can be determined pretty quickly during the initial interview. Test the candiate with some early tasks in different areas.