Hello all, all of these suggestions will be based on the lore of WARHAMMER and will be made for mortal empires campaign.
To begin with all Beastmen and Greenskins starting positions which are wrong according to the lore.
Khazrak the One-Eye must start in the place of Morghur the Shadowgave in Nordland in war with his old enemy Boris Todbringer, Morghur the Shadowgave must start in Forest of Arden near Artois and Malagor the Dark Omen must start in Great Forest near Bechafen. Also the Beastmen will need a lot of changes not only in campaign. For beginning will be nice Beastmen to have better raid stance like that of Norsca which to decrease the upkeep of the units during the raid and also to be added a march stance. The starting position of Azhag the Slaughterer must be in Troll Country as a horde with main goal and quests in the south. The starting position of Grimgor Ironhide must be in Peak Pass near Karak Kadrin in Gnashrak's lair. The starting position of Wurrzag Da Great Green Prophet must be in Southlands near the cursed jungle as a horde with main goal and quests in the north to unite all the Greenskins. As a whole Greenskins must be more like Vampire Coast with both settled and horde play style. The starting position of Skarsnik must be in Karak Eight Peaks along with Belegar Ironhammer and Queek Headtaker maybe you asking how is that possible? I will tell you how, LEVELS, in the lore Karak Eight Peaks are the biggest under city of all cities with many levels in him are you still asking what that mean? If Karak Eight Peaks become a separate province city with eight levels(settlements stitched together which can be reached only by entering in the upper one from the surface or the the next one settlement stitched to your settlement). With the most upper level occupied by Belegar Ironhammer, the most lower one by Queek Headtaker and one of the middle levels by Skarsnik rest of the levels can be ruins or some occupied by greenskins or skaven. These 3 campaigns can be best campaigns for head to head campaign, let the battle for Karak Eight Peaks begin. Troll Country needs a lot of changes first of all a little bigger size and norscan settlement near the coast also Throgg King of the Trolls must start in the northern part of the Troll Country near the mountains with his lair of the Troll King. Also all kislevite settlements need to be moved a little in south. Heinrich Kemmler starting position must be in the Vaults in the place of the starting position of Belegar Ironhammer.If in the future Araby is added Arkhan the Black may start from his tower near the black pyramid of Nagash. And Tiktaq'to may start in Macu Peaks near Hexoatl and with alliance with Lord Mazdamundi and in war with Blue Viper Savage Orcs. Also i think that the Cylostra Direfin must be somewhere much more in north in the Clawed coast maybe, with starting position in the twisted glade.
P.S. if i missed something feel free to tell me.