Now i just have to complicate it a bit more. 
You can do that with White Gel pen &/or fine (indelible) black liners.
The trick is to keep it simple. My own Kilt (yes I do own & have worn one)
has many more lines of colours on it than my wargaming ones, but from
across the table they look fine. Hold your figure at arm's length because
that is how far (at least) that it will normally be seen from. Remember the
eye might well tell the brain everything, but the brain is lazy & only deals
with the absolute basics. That is why we can look at a cloud & think we see
a car, dog, bunny rabbit etc. etc.