I talked about this in another thread with another user and i gave a suggestion to make missions simple, but at the same time make them better than in Mordheim: Have offensive missions or raids, defensive missions and exploration missions.
The first two are simple: in offensive missions you have a clear objective when you attack the territory of an enemy gang and escalate the offensive until a certain decisive mission where you drive them out and you claim the turf from them. In these missions you have a clear objective: destroy a water depo, blow up a weapons caché, reach a mineshaft, etc... and the enemy gang will have to fight you in order to defend the objective and rout your gang.
I also added that if you complete the objective, you win the mission instantly but you get less loot than if you made the enemy gang rout. I explain that this is mainly because you didn't destroy the objective and thus, you can use said objective. For example, if you steal the weapons instead of blowing them up, you might get gear for your gang. If you don't blow up the water depo, you might sell the water and get a bit of money. I want to add this to make players consider during battle if they should use the advantage they have to get greedy and steal the objective instead of destroying it.
Defensive missions are quite self explanatory: the role is reversed and you have to prevent an enemy gang from fulfilling the objective. In this scenarios i really want to have introduced the use of screamers and stummers as some sort of alarm that will give you the rough indication of where the enemy might be.
Meanwhile, in exploration missions we return to the mordheim formula: random runs in the search for gear and goods to sell and you happen to run into an enemy gang. This missions should be totally random since they are temporary opportunities to get stuff for your gang, like archeotech (very valuable loot) and some hidden weapon storages.
I think this would spice up the mission variety a bit as long as they use the mission scenarios we have in Necromunda, which are really good.