If you are new, i advise you to start fighting “Bandits Thugs” & “Bandits Marksmen”
The Undeads are also quite easy to fight. Especially the ghouls, skeletons and “Zombies”(wiederganger?).
Avoid Orcs & Goblins at start !
The easiest to the hardest :
Bandits Thugs / Bandits Marksmen / Bandits Raiders / Bandits Leaders
For the Undeads :
Wiederganger / Ghouls / Skeletons /Skeletons guards / Fallen Hero / Necromancer (weak, but very powerfull magic)