You can’t decide your battle formation yet, but one thing is certain: Monsters you meet will always seek to outflank you, even if you outnumber them. Move your strongest defenders to the flanks if you have the time, with orcses you will have the initiative in the first round. The guys holding the middle can easily mop up the orc young thrown at them and then go help the flanks. Carry extra weapons and shields, the orcses will crush your shields and your weapons will wear out before battle ends. Snipe at them with xbows. Target berserkers first, unless you have better shots at lightly armoured orc young. In melee orcses are easily hit, but you need many of them before they go down.
Wiedergangers are easy to defeat, they reanimate a lot which is annoying, but easily controlled. Ghouls are easy most of the time; annoying when they feed when near death as they get fully healed.
Beware armoured skellies with polearms/two-handed swords. Xbows should be fired at them exclusively to destroy their armour as quickly as possible, goblin crossbows are extra good as they often push the target back by one hex on hit.
When facing necromancers try to keep one (per necromancer) of the weak skellies in the front of your line down – they will get ressurected to block your way to the necromancers. Preferable to having the stronger skellies at your flanks (every time at your flanks, they don’t believe in frontal assaults heh) ressurect repeatedly.