The best time to clean your cast iron is when it is still hot and you should never use soap or anything abrasive such as steel wool.
The easiest method of cleaning your cast iron is to boil some water at the same time you are making dinner. When you are finished cooking in your cast iron pan, pour some boiling water in. Use a rubber coated spatula to slowly stir and scrape any remaining bits of food of the bottom of the pan.
Once you pour the water off you can wipe the pan clean with a dry paper towel. The pan must now be reseasoned. You can do this by spraying lightly with vegetable oil or by wiping a thin coating of shortening around the inside bottom and up the sides. This will keep food from sticking to the surface the next time you cook and must be done each time you use your cast iron.
If food particles are stuck you can try baking soda or salt. Scrub gently with a plastic scrubber and let set for an hour or so. This should do the trick as the lifting action from the soda and the friction from the scrubber will help to lift any remaining burnt on food.
It can be hard to embrace the idea of not washing this type of cookware with soap after use but you will be very glad you didn’t. It really has more to do with submerging the pan in water while you are washing it than it actually does the soap itself. Your cast iron can absorb water and then become prone to rust. That is why it is advised to pour hot water into it (the seasoned interior which holds some moisture resistance) instead and not using soap which may strip the seasoned layer and allow moisture in.
Many campers enjoy cooking with cast iron. It is versatile enough to go from grill to campfire and has been known to last for decades.