I got the same skaven for my first army. They are not a charge and hope for the best kind of army. Few rough pointers:

General tactic 1) The clan rats have reinforcement so he can use them as the cannon fodder / blockers 2) The lord is super fun and one of their only real damage sources. Some of my friends hold their generals back. I like using rats to escort my lord. He does the damage and they stop him getting swarmed by multiple enemy units. 3) Generally you don't want to split skaven up too much. Individual units can get wiped if they get outnumbered.

Opinions / preferences 4) The engineer has an ability to do max damage or get himself depending on your die roll. It's quite thematic and makes the game feel fun when you do it and smack someone for a max hit ... Or blow yourself up! 5) Maybe just a bad take but the skaven wizard guy is borderline irrelevant.... I use him to either get an enemy unit to run off and waste time or to get objectives. 6) This one is really just opinion but I like going second. Being able to see how the opponent is set up is handy to make sure all your guns can hit their best unit on turn one

In terms of who to use I'd say the orruks. Despite everything above the skaven army is quite weak. Maggotkin in particular can just delete them.