Well, I wrote up a long reply this morning and it appears to have dissappeared in the aether...so will try again.
The golem looks like your paint may be a little thick which is giving you that "plastic" look. There are several wips to check out for skin tones around here. Bailey's sbs's are awesome. AndyG and TenBall did a friendly comp with a barbarian mini. Lot's of flesh and gives you an idea of how minor tweaks make a difference in the final outcome. For undead, imho SkelettetS wip shows the best looks possible.Check out BLood As Medium's wip. Not only does he have great skin tones, but is currently doing gorgeous alien skin on some GeneStealer's. I have five different skin recipe's provided by various people. Iirc this one is from either TenBall or AndyG (maybe Trystan). Anyways, i think they are all Vallejo paints and after using the recipe a couple of times it makes it easier to tweak it or just go your own way.
Base Coat
BC. Brown Sand 100%
Highlights
H1. Brown Sand 75%. Basic Skintone 25%
H2. Brown Sand 50%. Basic Skintone 50%
H3. Brown Sand 25%. Basic Skintone 75%
H4. Basic Skintone 100%
Shadows / Shading
S1. Brown Sand 75%. Burnt Cadmium Red 25%
S2. Brown Sand 50%. Burnt Cadmium Red 50%
S3. Brown Sand 25%. Burnt Cadmium Red 75%
Highlights
H5. Basic Skintone 50%. Ivory 50%
H6. Ivory 100%
And page 100 of White Dwarf 362 hasa detailed skin recipe.
Hope that helps,
-Mike