Many people set out to stain their own deck but do not realize that just slapping it on can have less than mediocre results. There is a little more to applying deck stain than just squirting it on with a pump sprayer or slapping it on with a brush. Applying a deck stain evenly is going to ensure a nice even professional like finish. It can also help ensure proper stain penetration and reduce the chance over applying, which can lead to a blotchy finish that ends up flaking off.
First wash the wood surface with a wood cleaner, brush, and/or pressure washer. Follow up the cleaning with an application of deck brightener to help open up the wood pores. After the wood as dried for a couple of days it is now ready for stain. Most deck stains can be applied using various application tools. A brush, stain pad, roller, or an airless sprayer can all work well. Use whatever tools work best for you.