The first important step is to choose the stain, or perhaps not to stain at all. If you have a “pure” type of wood such as cherry, or oak, perhaps mahogany, it might be that you choose to pass on the stain. Bear in mind that sealing the wood will significantly darken it. Staining isnt mandatory, its just customary, and is based on the human need to color code things, such as matching the wood of furniture.
Assmuning you want to stain anyways, choose the type of stain. It may be applied by using a cloth or a brush, either way is efficient. The beauty of using a cloth is that it eliminates a need to clean the brush. If you want a lighter color than the stain is providing then simply wipe some off with a second cloth. On the other hand if you want a darker color simply apply a second coat, after the first has dried.
The next part of the process would be to seal the wood. Stain ends up looking blah, sealer rescues it by providing a nice shine along with protecting the wood. Be sure to stick with the level of sheen you choose in your sealer, “satin” is highly shiny, whereas semi-gloss is only mildly so. If you put one coat of polyurethane after 2 coats of varnish… well it will be a tragic mess.