Do you strum a guitar up or down?
Most people have the pick angled downward towards the floor when they strum. Some people have the pick angle more parallel to the strings, and some people, angle the pick upward. It really doesn't matter.
What is the proper way to strum a guitar?
To learn to strum the guitar properly, you need to keep the elbow of your strumming hand out of the way of the string, near the base of the guitar, so you can use your wrist to strum. Support the guitar neck with your fret hand. The thumb should be positioned just past the center of the neck (opposite the strings).