1. Over Washing
If your skin has been overly dry, or if it feels "filmy", like there's a built up layer of dead skin, you may be washing too much, and drying your skin out.
Washing too much causes your skin to get too dried out. That causes your sebaceous (oil-producing) glands to jump into overdrive, and you end up with skin that's insufficiently hydrated but oily. It's like a recipe for breakouts.