That’s a great question! When I want to play my Spotify playlists in shuffle mode, I go into the Spotify app, locate the playlist and tap the “Shuffle Play” button at the top. Then when you go to play the playlist via Alexa on your Echo, it’ll be shuffled! So the next time it plays via a routine, it will start from a different song.
If you want to play the songs in order and “un-shuffle” them, go back into the Spotify app, tap into the song that’s playing and then tap the two intersecting arrows icon that’s directly to the left of the larger “back” button icon.