In and around LA, the freeways are always packed. When you finally get there, expect a hell of a time finding parking. My tip: don't drive anywhere, walk. See if you can get on a treadmill and walk fifteen miles straight for practice. Bring a backpack with all your gear so you don't have to make trips to the car. When you do leave, if by car, leave early or late to beat the traffic (it probably won't make a difference).

be sure to rent a car - it helps a lot to  travel around!