The trick for the smearing is using q-tips on these heads. It allows your to move the paint into areas gradually to give natural shading. And if you don't like it, you just wet another one and take it off. Apply the paint with a tiny paint brush and then work it around with the q-tip. This technique lets your play the trial and error game until you get it right. I can't really give you an exact ratio for the paint.. but it's not as thin as a wash.. maybe about a quarter of the volume as water? I work on a piece of carboard and use small amount of paint and water. I always do a final mix flesh tones directly on the back of my hand for colour matching or difference. Bear in mind 'scaled' paint is never like 1:1 pain, the colours change with scaling, usually darker,
Experimenting on a spare head that doesn't matter is definitely the best way to learn.
Your eye for colour is going to help much, much more than 'perfecting' this technique though.
Trying to match an existing skin tone on the head so it's invisible where you painted is a great exercise in colour matching.
I hate doing uniform sealing of a portrait as it sucks all the life out of it. I usually mix up varying satin, matt and gloss finishes to seal different areas with. Even doing grades of satin and matt randomly helps. I never buy into a lot of this sealing your work with coats and coats of varnish mentaility. I mean, it's not an action figure your grabbing the head of and wrenching around. I've got resin kits I painted 25 years ago and have barely one coat of a sealer on them and still look the same. Just use quality paint or brands that have earned your trust. I stick to Createx, Vallejo and Jo Sonja these days for most everything.
Good luck with your experiment! Feel free to post your results or ask me questions via the messaging on here. Only too happy to help if I can.
