Having had this whole "best chance of survival" thing drilled into me, I would generally be more inclined to stop severe bleeding before worrying about whether or not there's a bit of grit in there. If it's that bad, you're off to hospital anyway, so don't sweat the small stuff and make sure you, or they, don't bleed to death.
If it's "not that bad", then any of the above advise is good. The only thing wrong with boiling water is the amount of time it takes.
PS I think it would be useful to add our qualification when given this sort of advice so people can make informed decisions of their own. I'm gonna pop mine in my sig.