Seasoning the Pan
The pan has to be well seasoned (oiled) for there to be any chance of it not sticking terribly. Most pans come pre-seasoned, but each time you wash them you’ll need to re-season. To do so simply pour a bit of oil (any kind) in the clean pan and rub around with your fingers. If the pan is already warm from the cleaning, this will help the oil soak in. If it’s not, then put it on the stove top for 30 seconds to heat it which opens the “pores” and helps the pan absorb the oil. When cool, use a paper towel to wipe off excess.
If you want to give the pan a super-charged oil soak, the best oil to use is flax oil. It is very rich and seems to seep into the pores better than other oils. Pour some in, spread it around, then put it in a warm over for 1-2 hours. Consider this a spa treatment for your pan.
(Not) Washing Up
At washing-up time, consider not washing. If you practiced patience, then only tiny bits should be left. Just use a paper towel to pick up the bits and put it back on the stove for tomorrow. Unlike a non-stick pan, cast iron only gets more seasoned the more it’s used. (But if it gets too much use without a thorough scrub, it will start sticking.)
When you do wash, use a scrub brush and hot water. Never detergent which will strip all the oils*. Best “cleaner” to use is salt. Rinse the pan in very hot water to remover surface bits, then sprinkle salt over the pan and with your fingers rub it around to gather the food bits. Rinse again with hot water and repeat. Dry pan well. Then season the pan right after it’s washed and while it’s still warm. Should your pan ever rust, scrub the rust away with the above method, and re-season.
*If detergent does accidentally make its way into the pan, rinse well and season thoroughly.