LaTeX's standard styles use two page styles, one on normal pages and one on opening pages with \maketitle or \chapter, etc. Unfortunately there is only easy access to changing one of these two so if you want something other than plain on the opening pages you must use \thispagestyle on each such page. The fancyhdr package does provide a more flexible interface, but if you just want an empty page style on all pages then this package will do the job.