The most common thing that I do is do a high-pass at 250Hz, immediately. From there, depending on how warm the vocals need to sound, I will cut anywhere from 500-1k, varying on how deep I go with each vocalist. Almost always roll off some high-highs, like a low-pass at 12kHz, and then boost around 5k for some air if needed. Compress to taste and since the area that I have setup for vocal tracking is pretty dead, I'll add some light room verb to give some depth. More if needed, for like black metal and such...but then I will go with some delay and maybe use some verb as well to get desired effect.
Usually for comp on the vocals I go with around 20ms attack, 130ms release, threshold accordingly, and about 2.5:1 ratio, or more, but these are the general starting points. For heavy screamers I will compress the shit out of them, 4.0:1 ratio and 15ms attack, -40 threshold. Just squash it like crazy.
~006