I've been going full strength for both coats, although Michael Mutmansky has done some tests which indicate that may be overkill. I use pipettes with pumps to measure my volumes and have found that when I use a brush, an even coat takes about .2 ml of total sensitizer+metal salt per 10 square inches. For instance, an 8x10 is 80 square inches, so I use .8ml FO and .8ml Pd. The one time I measured, I got about 24 drops per ml. I may do some experimentation with diluting that first coat by 50%t and see if I notice a difference.