When my husband and I bought our house it took up every bit of our savings just to manage down payment and closing costs. It hadn't occurred to us that we would also need furniture to fill the place. Luckily, we have several good flea markets in the area and so were able to find affordable furniture that could be fixed up to look respectable enough for the home of two college professors.
Our finds usually fell into two categories: those that simply needed a good cleaning, those what needed refinishing to bring out the wood, and finally, those that can probably only be made acceptable by covering with paint.
CLEANING: One of the easiest and most affordable ways to clean up old furniture is with Murphy Oil soap - a mild soap that won't damage the wood finish but is very effective in getting rid of the grunge of ages. I use this as a first step no matter what shape my flea market finds are in. Sometimes a piece that you would swear needs refinishing looks terrific with a simple cleaning.
Another effective and quick way to refurbish a piece is to use a mix of linseed oil and turpentine - I use three parts turpentine to one part linseed oil.
The turpentine cuts through softened old finishes, while the linseed oil feeds the wood so that it won't dry out. If this produces an acceptable looking result, and you aren't prepared to spend much more time on the piece, then finish it off with another linseed oil/turpentine mixture - only reverse the proportions. A mix of three parts boiled linseed oil to 1 part turpentine will give the wood a very natural finish, with just a delicate sheen to it. The turpentine simply helps the wood to absorb the oil, and speeds up drying time.
REFINISHING. If you have a piece with a scratched and scarred finish, you have two choices - you can strip it and give it a clear finish, or you can strip it and paint it. If the piece has inlay or a lovely pattern of wood grain you will probably prefer a clear finish; if the piece has absolutely nothing special about the wood, or is made of mismatched woods (as many old and inexpensive pieces were - they were made to be painted.) then you will want to use paint.
The easiest way to refinish a piece is using what is called a "Furniture Refinisher." This is a thin liquid, very different from paint stripper, which is quite heavy bodied.
Pour some refinisher into an old coffee can and dip a piece of super fine 0000 steel wool into it. I usually cut a new pad of steel wool into quarters. Take the wet steel wool and start rubbing the piece of furniture, using circular motions. You will see the finish start to dissolve.
Continue to do this, rinsing your steel wool frequently and changing to a new piece as needed. As the refinisher gets dirty, you may want to discard it and add new.
When most of the finish is gone, use sandpaper to smooth the finish. Medium grade is good for starters, with fine sandpaper as a final sanding. Real fanatics (and I confess that I am one) will go up to 600 sandpaper or higher if available. The smoother the wood the more it will glow even without a top coat. How fine you want to go depends on the value of the piece in your mind, and the amount of effort you want to put into it.
When finished sanding, use a tack cloth to get rid of any clinging grains of sawdust and prepare for a new finish.
RECOATING. My personal preference is to use tung oil for a final finish. Many people prefer to use polyurethane or varnish. But for me tung oil goes on easily and dries to a gleaming finish and nourishes old wood in the process. Its other advantage is that it won't flake like a top coat would do - it is absorbed into the wood. If spots do wear away, you can spot refinish instead of having to start all over again. And it's easy to apply - take a soft cloth and rub it into the wood in a nice, even coating.
And there are those who like a waxed finish. Well stripped and prepared wood furniture lovingly waxed with a good grade of furniture wax assume a patina that is worthy of the finest antiques. It takes a bit of elbow grease to run the wax into the finish until it is absorbed - but the results are worth it.
It may be that you would like the wood in a different color than it really is. There are many stains on the market that will allow you to give your piece a finish color similar to pine, oak, mahogany - or even fantasy colors like pale blue or green. These need to be applied before the final coating, unless you use a worksaver that combines stain and polyurethane is one jar. This product goes on as easily as tung oil, but is a bit more exciting because you can see an immediate difference in color as well as shine. Note that if your wood is badly mismatched so that portions are a light colored hardwood and others a darker softwood (or vice-versa) you will need to choose a dark stain to hide that difference.
Unless you use the one-coat finish, you will want to stain your wood, allow the stain to dry and then protect it with polyurethane.
If you dislike shiny finishes but want the ease of a polyurethane coating, try this trick. Apply one coat of high gloss polyurethane to the piece. Let this dry until it is just a wee bit tacky. Then apply a coat of satin finish polyurethane over the gloss. The result is very close to the glow of a hand-waxed finish - but much more durable.
This is the only finishing technique involving polyurethane where you can recoat while the first coat is not quite dry. If you want two coats of the same finish, make sure the base coat is thoroughly dry.
Apply your clear finish with long, sure strokes, going with the grain of the wood. Then wait patiently for it to become hard and dry.
Then step back and admire the treasure that you have resurrected from doom and gloom with your own two hands and a bit of elbow grease.