Beating the roadmap missions can be a whole lot tougher than beating the world map ones. Usually they will consist entirely of walkers, though, which simplifies the strategy. For one thing, the trait matching won’t be very important because most walkers won’t have traits. Instead, try to fill your party with survivors who have adrenaline rushes that trigger a critical hit, since that’s instant death for any walker. Also, equip weapons that increase the chances of a critical hit.
Join a faction and take the strongest leaders with you as the sixth party member when you go on the roadmap missions. If your faction doesn’t have four-star leaders as the strongest, then leave it and join a different faction. If you have a REALLY strong faction, you’ll find a few people with five-star leaders. Make sure to set your rarest and highest-leveled survivor into the leader position so that they pick yours as well. You’ll get rewarded for that.
The time to buck this advice is when a tournament is actively happening in the raid area. Save all of the good leaders until then. Or if you’re a real sneak, leave the faction after you use up their good leaders, and then join a new one so that you can automatically have more good leaders to play with without having to wait for the cooldown timer to end.
The training ground can eventually earn you three- and four-star survivors, but not until you upgrade it to level 11. After that, research the training that comes with it, because level 11’s training will unlock a random three-star survivor. Level 14 training does the same thing, except that it will also give you a chance at a four-star survivor. Unfortunately, none of the training camp levels will give you any five-star people yet.
When you are doing level ups, try to match sacrifices who have the same persona as the survivor that you are leveling up. The persona will be rebel, peacemaker, etc. You have a small chance at an instant upgrade when you do this, with no max-level shenanigans required. The more persona-matches you sacrifice at the same time, the higher the chance for an instant upgrade.
If you run out of food or wood, or simply run out of space for survivors or weapons, sometimes the best solution is to sell them off (especially the weapons, since you can’t do any sacrifices with them). They won’t earn you much, but they will free up valuable space in your inventory. Or go and level up so that you can hold more at once.