I've found that starting a split in the center of a stave and work out towards each end will generally give you a cleaner split.
Pat, what do you use to start your split this way? I usually do this on small trees / big saplings if I’m trying to get two staves out of them. This really helps with runoff, but, for me, it can be a pain to start the split. I usually drive a hatchet till I can place my wedges, but I’ve had a bunch not want to open up. All elm so I guess it may just be the wood.