MANY LAYERED GLAZED PAINTINGS; have you experienced "drift" ? it's that tendency for the features in a figurative, many layered oil painting to grow (outward usually) more with each pass, as you very quickly loose any guiding lines you may have had in the first layer, you don't notice how far off your proportions are in subsequent ones, until all of a sudden the subject of your portrait looks slightly demented.. common "drift" problems; eyes too big, too far apart,eyes "crooked" or asymmetrical, nose too long, area between nose and upper lip too short, nose too wide, mouth too wide and too long..i have my own personal problems with drift atleast once , and usually more with every painting. keep re confirming your proportions as you go...in the excitement of paintng it's easy to forget.