Plex is happiest when the tracks are organized into real albums, because it looks up metadata. So for your Sons of Anarchy track, I would folder & name & tag it as if it was the Sons of Anarchy soundtrack, where that is track 3.
When that is not possible, or when you have so many loose tracks that it’s a PITA, I think the next best thing to do is to create themed “albums” under Various Artists.
My loose tracks collection is an album named Zzingles, with the Album Artist set to Various Artists, and each track’s Artist set to whatever it is.
M:\audio\music\Various Artists\Various Artists - Zzingles\Some Loose Track Name.mp3
Plex can’t look up metadata for this album or tracks… The album is fake which screws up all auto matching. But it sees the files and it knows the title and the artist, which is good enough to find it and use it in playlists.
I do something similar for dance music where I have a crapload of loose tracks… The album is “Club Misc” and the Album Artist for each track is Club Tracks. This works OK in that the music is organized and isolated, but Plex really hates the Album Artist name Club Tracks because it cannot match it to something. So, I see garbage like this… It picked some random artist as the photo and bio for Album Artist Club Tracks. Oh, and there are two of them. Oh and if I change the picture, Plex eventually changes it back. 
However, the final result is tolerable: all those misc tracks are captured in one album and they are findable by track name and artist name.
The dance music situation here would work better if I put them under Various Artists, because that’s a magic term that means something to Plex. It doesn’t try to look up Various Artists, it knows that means it’s a compilation. However, I do not want those files mixed together, nor did I want a library just for dance music, so I tolerate the weirdness.
(One major downside that is not apparent at first is this: Plex does not seem to understand per-track genres. Genres are applied at the album level.)
Plex has some very strict limitations in music handling. It’s pretty OK if your stuff is all arranged into “real” releases like albums and EPs. If it isn’t, you have to figure out the least objectionable workarounds. There’s no wrong answer, but there is no right answer either.
