Oilpaint is a pain to use because of all the material, cleaning etc (use water miscible oil paints, with them you swap out solvents for water! Easy to clean too, just use soap, and no toxic fumes!), but as it takes ages to dry, it's actually very newbie friendly, move that paint around, add in more paint or even scrape a bad part off! And ofc, paint on top of dry paint.

That said, it's probably the hardest to master.