First thing is to get some really good grain sealer on the ends to slow down the water escaping. You will get end cracking anyway, so be sure to leave it longer than you want to end up so you have room to trim the ends later.
If the pith is left in the log, it will almost always crack anyway, unless dried very slowly -- depending on species of course. Fruitwoods are particularly prone to splitting/cracking. Walnut can develop cracks really quickly, even when sealed. If you aren't going to use the cants right away, it is best to leave the logs as long as possible, with the bark still on. Cut them down when you are ready to use them. That will keep it in better condition. Wrapping in plastic may work or may stop too much water and make them mold. Paper bags may work too. It mostly depends on your local environmental conditions.
If you carve it green, put an expansion cut in it that is deep enough to get to the pith. That will generally control the splitting. That assumes you can find a way to fit the cut into your design (like in the back).
