What is the best way to drive southbound through L.A. on a Friday afternoon/evening before Memorial Day?

My girlfriend and I are finishing up a long road trip and are heading back to San Diego from Carmel, CA. We didn't have any specific plans for the road trip, and find ourselves trying to make it back tomorrow, which happens to be the Friday before Memorial Day, which means traffic. Any suggestions on the best way to get through L.A. relatively painlessly? There are 2 of us, so carpool lane suggestions are welcome as well. I just know L.A. can be a parking lot sometimes, and I really want to avoid sitting idly for hours on end if we can keep moving and make decent time. All suggestions would be greatly appreciated!