I purchased 2 AB 800's along with stands and umbrellas and have been starting to get to know them but have questions on the placements. I plan on taking pictures of couples and singles in the near future. Any good rules of thumb on placement of the key and fill lights? How far away from the subject? Also have questions on light metering with the L 358. It seems that I take a reading and set my camera but the histogram is still showing spikes on the left and right, I have been using a 3 to 1 ratio. I am shooting a 300D.