Take #1*mL# volume of the undiluted sample.........and place this is a #10*mL# volumetric flask........make up to volume....this concentration is #1/10# of the original concentration.......
Take #1*mL# volume of the FORMER sample.........and place this is a #10*mL# volumetric flask........make up to volume....this concentration is #1/100# of the original concentration.......
Take #1*mL# volume of the FORMER sample.........and place this is a #10*mL# volumetric flask........make up to volume....this concentration is #1/1000# of the original concentration.......
i.e. #1/10xx1/10xx1/10=1/1000#
Of course, I might have a #1*L# volumetric flask; and thus I could take a #1*mL# volume of the original solution, and dilute this to #1000*mL#.