Hey Mu, nice to see some oils around.
well i hope i can help with the oil painting, as i have been painting for the last months and been improving and as im learning portrait painting right now i hope this will be usefull.
As i paint, i was taught to start with the darker colors and build from there to the lighter ones. Like you are doing it, but the difference i see, is that you are pretty much laying the dark color as a base color and having some difficulties to come with midtones and lights. Give it a try to block out areas with the dark (where is dark) midtone (where midtone) and lights (where is brighter) and after all is done come back to the lights and add the highlights.
One thing to remember is always to brush really soft so you won’t mix the paint on the brush with the paint already on the canvas, in that way you can lay a new layer of paint over wet paint.
You don’t need glazes (im not sure if glazes are what i think they are, since i’m thinking of velatura from the itallian) you’re not supposed to be doing them to bring lights up as far as i know. You should only use transparent or semi-transparent paints to do it, and over dark areas. This would give you a wash over the colors and bring them closer together. Titanium white is not a transparent color, but alizarin crimson is.
And the last thing, you could try painting with a reduced pallet for portrait painting. That would go ivory black, titanium white, cadmium red light and yellow ocher. You could add some burnt sienna also to help out. With that you could paint pretty much any Caucasian flesh tone.
Well hope any of this is going to be useful for you, it has certainly helped me a lot when i was told those things.
cheers keep it up 
Gabriel
