We need a smaller group then last time. Like 4 main people and have maybe one or two die over the course of the season. If we get a big group of 9 or so like last time, based on season 1 a lot of people will consider all these new characters walker food and expect major losses like before. With a smaller group they can focus more on how we interact in the group and maybe be able to influence the other three a great deal.
Imagine 3 Kenny characters. Kenny and Clem were really the only ones who we could influence as the rest of the group (Minus Lilly to a much smaller degree) were pretty well set in stone. A small group of four would allow much more character development which is what we will need a lot of to make any new characters stand out.
It would also help to have familiar sights while still being it's own story from 1. Maybe this new group travels through Macon sometime after the bandit attack and they check out the motor inn for supplies but find nothing. Or we get to see Kenny's RV on the side of the road or crashed somewhere. We don't need to interact with the bandits or Lilly but a little sight like that would be very exciting to see.