How do I decrease swelling in the face from injury?

Details???? Not much on detail here. How severe is the trauma? Fractures or a bump? Where on the face? How long has it been since trauma: the answer is from ice and advil (ibuprofen) to surgical intervention. If you got a big bump and then a lump, again advil (ibuprofen) and intermittent use of ice.
Depends. If facial swelling from an injury is due to a contusion, ice may help decrease the swelling. If the swelling is due to an infection, get evaluated by your physician immediately.