A simple way to think about finishes is to put them into two separate categories. Film based and penetrating oils. Films would be finishes that sit on top of the surface of the wood. Lacquers, polyurethanes, shellac, waxes, and varnishes are all versions of film finishes. These finishes have many different attributes including durability, reparability, toxicity, marketability, and skill required to apply them.
To simplify when and where to use these finishes I generally think these finishes are more suitable for objects of art as compared to items of utility since these finishes are more difficult to repair and require a skilled craftsperson to maintain them. Penetrating oils would be nut oils like Mahoney's walnut oil, linseed, Tung, mineral oil, and vegetable oils. These oils go into the surface of the wood and enhance most woods while protecting from the inside.
Oil finishes are much easier to apply than film based finishes and you can expect anyone could replenish the finish. Nut, linseed, and Tung oils will actually harden and become part of the wood. Mineral oil and vegetable oils will evaporate and require more reapplications. All oils darken the wood and some even discolor over time. Tung and linseed oil oxidize to a yellowish hue that could be undesirable on a lighter wood. Walnut oil oxidizes to an amber hue and in my opinion enhances the look of the wood in the years to come. Mineral oil doesn't color much at all except on the initial application.
Directions on how to use my oil:
Apply one heavy coat and let sit for an hour and then wipe away any excess. Your item is now ready to go. If the item begins to look dry over time reapply another coat.
If you would like more information on this subject please contact me.