I use oil too,
Before I applay the base color, hubrol perfectly cover and dryed by little hornet, I apply the same base oil color and with a big brush I remove most as possible, too as possible, to have to thinn film of oil base color.
I start with the lights.
On other place I light the same oil color, then I add it without waiting as little points that I wil smouth by a cleaned brush; if need I add other.
The same with the shadow.
If color is too liquid, Before I place it on a adsorbig paper, not cleanex handkercief, then I will rigenerate it with some Humbroll thinner.
Excuse my bad english.
ciao Stefano