the "best" way to take ketamine, if you ask a serious user, would probably be IM. There's no drip, it's rerlatively safe, since you'd be injecting a medical solution of ketamine, and you don't have to use as much to get desired effects. It's better than IVing becuase the onset is slow enough to get the syringe out.
Anyway, the best place to ask questions about ketamine would be the psychedelic drugs forum, what with K being a dissociative and all.