It's sensible to follow Howard Lyon's methodical guide to painting in a renaissance style without using actual oil paints, but as someone who learned with oils back in the day I would like you to suffer as I once did, and spend at least two weeks just getting through the tutorial. Here's method made simple and explicit as schools rarely do. Though an underlying mystery to the why of it—that your layers of paint should be translucent—is ironically not made clear.
The third goal is to be accurate. This is the least important, but still of great value. I say this because there may be portions of the painting that are near-impossible to copy with complete accuracy and paint in the same way that the Old Master did. If the original painting was done with big brush work that feels spontaneous and loose, you don't want to get out your smallest brush and try to mimic a single brush stroke with a hundred small strokes, just to show how meticulous you can be.
I suggest that painting with similar vigour and manner as the original artist will be much more valuable to emulate, than creating a ostensibly perfect copy that misses out on the original technique.
Previously:
• Great advice for those getting started in miniature painting
• This 1953 painting of the inside of an artist's skull has fascinated me for years
• Myth-busting the self-shredding Banksy painting
