Order totally matters. You gotta start with something that entices, but doesnt overwhelm. Perhaps a song with a long-ish instrumental intro, definitely a song that feels like a thesis statement for the playlist as a whole. Then you slowly ramp it up in intensity as you get to the middle of the playlist, where the bangers lie. Then you wind down and drop a few slow jams as you close it up.
More ordering tips, never double up joke songs, songs from the same artist, or place two similar tempo songs right next to each other. Space these out to make the playlist have more variety.
Of course, sometimes these rules are meant to be broken, but thats an advanced technique. When starting out creating playlists, its better to keep to the structure though.