01: know what 'postmodern' means in the context of the genre
'postmodernism' is a lucrative term spawning many and varied meanings. it typically designates a rejection of Victorian rules or the expansion thereof; meaning is truly contextual and perspectival and almost without rigification and absolutism. of course the extremes can be clownish (Dadaism) but that's just a natural consequence. in music, postmodernism becomes even more mercurial because the best you can do isn't reject a genre's format, but expand it and maybe add new elements. seriousness to do the latter on the part of the musician must be tempered by a knowledge of how unlimited the bounds of any genre are. so when one says that their goal is a fusion of different sub-genres it's always a questionable effort because some don't deviate from each other and each could be more varied than when initially surveyed. it's a laudable attempt, but often led by a false sense of progress. there's nothing wrong with trying to stretch one genre of music to its limits.

02: understand the the aforementioned fusion of genres may yield nothing new
take Coheed and Cambria, who've been said to derive their influences from Metal, Pop, Punk, and Emo. once again, accolades for the smorgasboard, but low marks for the fact that the influences aren't radically dissimilar. it's not that hard to articulate Punk and Emo--since the latter was born from the former--and Pop Metal isn't really an ingenious mix. the work gets bogged down in the effort to exercise entirely minor brushstrokes in the life of the painting. Coheed and Cambria don't sound that different from AFI or The Used, but lack some essential ingredients.

03: you can't always bring out a maximal qualitative difference by being lyrically abstruse
The Mars Volta and Dredg are guilty of it, but are forgiven because it's offset by overall good musicianship. one may even argue that Dredg became less convoluted after Leitmotif and the bifurcation of At The Drive-In into Sparta and Mars Volta made the arcane rock-speak more digestable. when you have song titles like 'Velourium Camper II: Backend of Forever' and 'Three Evils (Embodied in Love and Shadow),' it simply sounds too serious and threatens listenability [ad lib]. not to mention the fact that when Zeppelin were influenced by J.R.R. Tolkien, they could actually pull it off without looking silly.

04: vocal variety is key
no matter how important your lyrics or how good your backing band, if you don't sound different from New Found Glory's Jordan Pundik in a lot of parts, hardly little can save you.

05: quite a bit of postmodernism is garbage
learn to differentiate between albums that try to be new and different and the ones that actually are.