Some things I find helpful in painting faces:
Paint the undercoat with Vallejo flesh, since Polly Scale will dissolve when turpentine hits it and Tamiya flesh is too orange.
Don't be afraid to paint whites in the eyes. I view the whole argument about whites versus no whites this way: real clothes aren't shaded, but you shade clothing on a figure to make details visible that otherwise wouldn't be seen. Maybe painting the whites isn't completely realistic, but they add a lot more character to your figure's face, and they are the only way to make the eyes look up, down, or to the sides, since the whites define whre the edge of the eye is.
If you can afford it, use Winsor-Newton Artist's oils (not the Winton oil color) for your shading, they cost $10-$30 a tube, but the pigment tension is great (they stick better and don't smear off when you blend like with Winton or Grumbacher.) Winton is next-best, but not as good.
Be sure to thin artist's oil with a good-quality turpentine prior to laying in your shading colors, since unthinned oils have the tendency to spread all over a face when you blend, whereas if you thin them a little, they are semi-dry by the time you blend them, and only the edge gets blended. They also stick better.
Avoid red- and orange-browns for the shadow color, a walnut brown works best. Yellow Ochre mixed with white makes a very good highlight color.
Use at least a #0 brush for painting the shading, and don't use anything smaller than a 1/8" flat brush for the blending. The blending brush also needs to be the softest one you can get.
Use an orangish-pink color for the pink on the cheeks - NEVER use dark red or girly pink.
The last touch, a five 'o clock shadow, should be added with gray paint that's thinned to the point of almost being a wash. It's best to appy this to the chin and jaw but not to the upper lip, unless your figure hasn't shaved for days.
And don't work on your men while the oils are drying - you can wipe off all that work in one touch of your finger
Hope this helps!