To make a rust-preventive coating for tools, outdoor furniture and other metal objects, just combine 1/4 cup lanolin and 1 cup petroleum jelly in a double boiler over low heat. Stir until the ingredients have melted and are thoroughly blended. Next, remove the mixture from the heat, pour it into a clean glass jar with a lid and let it partially cool.
Using a clean rag or cheap paintbrush, apply the mixture while it's still warm. Don't wipe it off -- simply allow it to dry on the object. If there's any of the mixture left over, cover the jar tightly with the lid for storage, then warm the mixture again just before any subsequent use. Coat tools and outdoor furniture at least once a year, in early spring, touching up the coating as needed.
If you're in a pinch and don't have any of this homemade coating prepared, you can help protect new metal tools from rust by smearing a thin layer of petroleum jelly on them before you use them or before you take them outdoors for the first time.