Correctly Clipped - Good!
When you clip your rope into the carabiner on your quickdraw, look to make sure the rope coming from the climber is cleanly passing through the carabiner and traveling away from the rock as it's pulled up. The rope should be passing over the gate of the carabiner so that if the lead climber falls, the rope will be pulled down and away from the gate.
Back Clipped - Bad!
If you clip the rope so that it is passing behind the carabiner and moving in toward the wall as you climb, there is a chance that the rope could unclip the gate if you fall. This would make your fall much longer and much more dangerous than the average whip.
Remember that if the lead climber falls, they will be falling back and away from the wall. You want the climbing rope to also be coming away from the wall as it passes cleanly through the carabiner so that nothing gets tangled or unclipped in the event of a fall.
When you're lead climbing, sometimes your brain goes into survival mode and thinks, "MUST CLIP!" instead of "Let me think about this before clipping to make sure I do it accurately." We get it. So we have a few easy ways for you to remember how to clip safely and correctly. You can think, "Rock out," because you're definitely going to rock out on this route. Or you can think, "Up, up and away!" because, let's be honest, you are the Superman (or woman) of climbing.
Want to see clipping done right and the risk of backclipping? Check out this video: