Cracks develop in areas that have weaknesses or because the wood is abused and needs to move to relieve internal stress. Naturally, to minimize cracking, you want to minimize the stress. When you begin the turning process, you need to select logs that are fresh or have been stored so that drying is controlled. Cut off the ends of the log and see if checks are deep. If they are their in the starting material, they will be in the final product.
Some woods are more forgiving than others.
Our North Carolina soft Maple is very forgiving, but Apple or Cherry seems to delight in torturing the poor turner. Other woods like Red Oak is very crackable, whereas White Oak is a little less fragile. Magnolia, Elm, Osage Orange, and some others don't seem to crack as bad. Log Storage I normally split the log through the pith into two pieces after I get a log. Once the checking starts on the ends, it will progress rapidly through the rest of the log.