Can you tell me the basics in cleaning a firearm?
On any firearm that you hand to someone, or that someone hands to you, first, make certain that it is unloaded! Depending on the kind of firearm, open the action, check the bore, the magazine, cylinder, etc., to determine that there are no shells in the chamber, magazine, bore or cylinder.
Make certain that there is no ammunition in the area or near the firearm. Always keep it secured away from your firearms. Ammunition is not needed to clean your firearm. Open the breech, cylinder or receiver or remove the barrel if possible. Run several patches down the barrel, soaked with bore cleaner, or use the new "Bore Snake" or Gun Weasel" type cleaners. If the bore is exceedingly dirty, use a brass bore brush to remove heavy fouling. Make certain your cleaning supplies fit the gauge or caliber of firearm you are cleaning.
Clean the barrel until the patches come out clean. Use a toothbrush, cotton swabs or other cleaning tools to remove debris from the receiver and other hard to clean areas. Flush with a good gun solvent or gun scrubber to remove powder fouling and small particles. Compressed air is good if available to blow out the receiver and dry the firearm, caution being used not to dislodge any small parts. Make certain the entire firearm is as clean as you can possibly get it without removing difficult parts. Leave that to a competent gunsmith.
Finally, use a good quality light gun oil to lightly coat the barrel and moving parts just slightly. Do not use an excessive amount of oil in the receiver or action area. Store your firearm away from all ammunition and in a safe, dry place, away from unwanted hands and inspect it periodically for rust/corrosion.