Shellac. If you are using orange shellac (what is now called "amber") you might consider thinning it with alcohol about 3 parts alcohol to 1 part shellac. It will flow better and more smoothly and it will give a more consistent, but much lighter, color. You can then recoat as many times as you like to get progressively darker color. Let it dry well between coats and use 0000 or 00000 steel wool to smooth it out between coats. After the final coat, lightly scuff with the steel wool to smooth it out and remove any brush strokes and then apply boiled linseed oil and rub it in until it's dry. This will give a nice sheen to the shellac and also make the shellac less affected by water which can cloud and whiten a shellac finish. Nice thing about shellac, if you apply it and then decide it's too dark or not smooth enough you can wipe it with wood alcohol and remove it. Shellac dries, it does not cure, and remains soluble by alcohol forever, so don't spill your Scotch on it.