If your shoes have removable insoles in them already, take them out.
Match up your shoe's existing insoles with the ShoeCue and mark the size. (Note: although ShoeCue has suggested trim lines, this is an important step because every shoe is sized and shaped a bit different.)
With scissors, trim the forefoot of your ShoeCues to match the size and shape of your old insoles. (Note, be conservative with trimming, you can always take more off but can't add it back!)
Slide your new ShoeCues into your shoes in place of your old insoles and you are ready to go!