One of the appealing things about crafting a piece of furniture from wood is that it already has a pleasant colour and texture. You might not want to hide it under a coat of paint, and a good stain can really bring out the natural texture. Here's how to do it right.
In this video from This Old House, wood-finishing expert Bruce Johnson demonstrates how to treat a wood table and prime it for a perfect finish. The first thing you need to do is give the wood a light sanding along its grain; Johnson recommends you start with a 120 grit or so. (He also prefers to sand by hand, as belt sanders can be too aggressive.)
To avoid blotchy stains, he then applies an oil-based wood conditioner that will prevent the stain from pooling in unwanted ways. Once your wood is treated with the conditioner, you don't have to be particularly neat when applying the stain itself and you can use a paintbrush, rag, or whatever works. What matters more, according to Johnson, is wiping it off. You need to wipe off the excess stain that the wood hasn't absorbed.
Finally, he lets it dry for around eight hours before applying a polyurethane varnish (stirred, not shaken!). In this case, you do want to use a decent brush and not a cheap sponge so as to avoid air bubbles. One key thing to remember is that if you started with an oil-based conditioner, you should follow through with an oil-based varnish. (If you start with water-based, then stick with water-based.) Johnson finishes up with a light sanding after the table has dried and does another coat for a resilient finish. Watch the video for the full explanation.
How to Finish a Wood Table [YouTube]