Oil paint needs to be diluted and, conversely, thickened. Become familiar with the various accessories!
Both are used to fluidize paints and clean paintbrushes.
If you work regularly with oil paints, get your thinners in large bottles, which cost less. Note also that you can recycle your solvents by allowing them to settle in the container after using them.
Media alter the behavior of oil paints by accelerating or retarding its drying, by accentuating its natural brilliance or fluidizing it: this is why they are commonly called "siccatives." Here are the main ones.
Once your work is finished, protect it from the ravages of time, pollution and dust by varnishing it.