Probably no one sure fire, always works for me method. One way may work one year and be found wanting the next, given state of cuttings when we take them and growing conditions til they are mature enough to set out or repot.
Trend in the industry seems to be several cuttings = more quickly sellable plant or fewer failures per pot.
Rick, I was thinking that the egg carton was a good way to keep things upright, too. Was also thinking that the carton styrofoam was flexible enough to almost totally seal off rooting area from above ground and thus minimize conditions for rotting as roots emerge. If the cuttings are in damp moss(can't tell from pic) that should be enough moisture for rooting.