* My favorite, I read a report/comparison one time that said that 3-IN-ONE prevented rust as well or better than other "protectants". Works for me, it's inexpensive and readily available.
I coat all exposed surfaces lightly by application with a Q-Tip or a larger soaked rag, say about 8x8 inches. The rag need not be dripping with oil. I usually take a fresh rag, put large drips about the size of a nickel, in a cicular pattern about 5 inches in diameter, on the rag. Squeeze the rag into a ball and store in a glass jar with a lid. After a day or two, the entire rag has absorbed the oil. I usually use seperate rags for the action and external blued surfaces. This keeps any powder residue or heavy greases off of the blueing. I resist the temptation to wipe down the wood stock with the oily rags though some folks do it that way.
When the rags become soiled in appearence, they are replaced.