2)Play fast, but make it catchy. Legitimize the blast as the defacto beat, make 190 bpm groove with downbeat accents. The music isn't a machine gun, and it's not a scalar exercise—it's a pounding, throbbing train.
3)Slop is charm. Mistakes are left in. In this way, the music retains its human element. Grindcore is music for people, not math for robots.
4)Vocals must be decipherable. Growling is a great effect, but it doesn't carry a song. Purposely leave "signposts" for the listener with enunciation. Those are the moments the listener yells along to.
5)Above all, defer to the masters, the designers, Repulsion and Napalm Death, and the myriad of bands that inspired them, like Slayer, Siege, Larm, etc.