I'm waiting for the Mortal Empires campaign. Whats the point of playing Dwarfs when I cant KILL SOME FOOKIN ELVES. Except I'll probably just play Empire because they are the best version of Tolkien humans. By which I just mean Renaissance Fantasy > Medieval Fantasy any day of the week.
To OP, Skaven are the most micro heavy army of all the factions in both games so far (Except the particular build of Chariot Spam Norse), go play High Elves first, they're the Empire of Total Warhammer 2. If you insist on playing the rat fucks a few things you need to keep in mind.
1. Skavenslaves don't impact morale of your real troops and cost pennies. So having some dumbfuck with a literal fullstack of them follow your real army to act as bulet sponges untill the elves run out of ammo is a great strategy. If you do not have a top of the line CPU this will crash the game though because that's a simply retarded number of rats onscreen at once.
2. More sensibly, that spawn rats spell you get every battle should be used as you start to engage the enemy army in their archer lines. Archers can't shoot-fire when busy trying not to get stab-killed as the rats would say.
3. Basic Clanrats are trash as a main unit. Stormvermin should be the core of your army. Or at LEAST clanrats with shields.
4. Magic. This goes for every army. Magic is absurdly powerful if used right. Grey seers can nuke half a units health if they aim it right, Malekith can raze entire frontlines if his little Sword Tornado spell goes the right direction, and the Slanns buffs are absurdly powerful as well. Get yourself a wizard in your armies as soon as you can
Realtalk though go play some High Elves, their basic archers are fucking absurd.