A good rule of thumb is that the larger the mod's scope, the greater the chance that it will fuck your save up when you tinker with your preferences. Most modders will be happy to answer your questions regarding compatibility issues. For best results you should select your mods before starting your gameplay session.
Mods that change your gameplay can and eventually will mess up your save if you keep adding them during your current session. Things like reskins, lighting mods, and texture mods are examples of cosmetic mods. Cosmetic mods are just that, cosmetic, you can generally add or remove mods in the middle of your playthrough without ruining your current campaign.
Luckily for you total war games in general have a large and vibrant modding community, and the popularity of the Warhammer total war game means that there is a bewildering variety of mods that shake up the game down to it's very core.Ī word of advice on Total War mods in general.
So you are bored with the vanilla game after a while and want to play around with more cool stuff or just sad that your favourite character was not included by CA.