Slipping knitwise or purlwise will look different. Try them both. If you start doing it one way and change your edge could look rather odd. Patterns usually specify if it is to be slipped knitwise, unspecified mean slip purlwise. Mainly, be consistent.
Cheating is an option. . . . Cheaters never win and winners never cheat, but smart knitters who want to retain an iota of sanity do, cheerfully. ~~Kory Stamper