I have used oil for years,
Mainly for flesh but also for warpaint, and brown washes for clothing, weapons etc.
Flesh Pink Brown
Brown wash - Raw umber is best
Black Paynes grey
Red - any just choose look
Olive Green can be used for other items
My technique is to push smallamount on pallett then use thinners to thin down, bruish application is more controlled and you can thicken with more oil or thin out with thinners. the benefit is you have a good amount of time to remove either through (cotton wool buds or brush with lots of thinnners)
As the oil is drying you still have time to take more oil off and can even use thumb to gently wipe across the figure creating hihglights of the bare paint under neath.
What takes time is working out the right amount to put on a figure as it can appear to be not enough but when it drys out can look heavier than at first.
Flesh, warpaint all oil on these
Flesh and clothing done with oil on these
all done with oils