One thing you really need to be aware of when climbing is how the direction you’re climbing in relates to the direction the carabiners on your protection are facing.
The rule of thumb is that the carabiner that the rope is clipped into needs to be facing AWAY from the direction of travel. Why? Because if you fall, the rope can force open the gate of the carabiner and become unclipped, resulting in a bigger fall. (Think of it as a cousin to back-clipping.) This is how it happens:
So what’s the solution? Make sure the carabiner (either the bottom biner of a quickdraw or whatever carabiner is attached to the sling or piece) faces AWAY from the direction of travel. Like this: