Initial starts in TW games can be wildly different depending upon who declares war on you. For ex., in Mortal Empires, sometimes when playing as Morathi big alliances of High Elves declare war pretty quickly at the start, and then the lizards declare war around the same time - against this many stacks, there’s pretty much nothing you can do other than fight an endless battle of attrition and rely on tons of magic just to hold the line. So it could just be you’ve got too many enemies and not enough troops at that point. One time as East Rome in Attila i had a “Likes Eastern Romans” and “Defensive” counterpart in Sassanid Persia (the actual traits of leaders in Attila was randomly rolled every game). That made the game about 100x easier - living my Best Dark Age Life.
So do everything you can to get some decent diplomacy with your not-yet-enemies and try as hard as possible to fight only one front at at time.
Another somewhat cheese tactic - something you can do far more cheesily with the Tomb Kings, is just make as many stacks with as many cheap troops as possible and auto-resolve every fight. The autoresolver overweights numbers vs. quality and it will consider you to be much stronger than you are with two trash stacks vs one medium tier stack.