Out of curiosity is this your first iso-rpg? Anyway Like the others have said playing smart and positioning are key and can make your life a hell of a lot easier. Your companions knock-down and stun skills are your best friends especially at the start when you don't have a lot of other options available. Teleport is also a amazingly useful skill if you think outside the box, sure you could use it to hurt a single enemy or you can use it to drop a water barrel in the middle of a group and then electrify it to stun the lot, drop tables on clustered enemies or to block doorways (oil spill is also great for blocking paths and cheap too at only 3ap), hell I've even used it to drop my melee fighters into a better position to battering ram as many enemies as possible in one shot. It even has some good out of combat usefulness like lifting chests or keys out of trapped areas. And although I've never tried it myself there is a flee combat button so you could probably reduce their numbers a bit, runaway, heal and then return to finish them off.
One handy thing I've only recently started using is the "leech" trait and it is amazing, pretty much every time you are hit you'll bleed a little and leech soaks it right back up and heals you. The healing is pretty good but the main benefit I've found is it stops me from shocking my own guys who before would have been 9 times out of 10 be standing in a blood pool and been zapped along with the baddies.
As for the game having linear progression, thanks to exploring a certain area with my lowest perception character (pretty dumb on my part) and missing a key item I found myself at lvl 10 with nothing to fight except mobs of lvl 14-15 and apart from the awful chance to hit % (solved by keeping them knocked down/stunned/frozen to get 100% chance) by playing smart and using choke points I even managed to kill some bosses. It was actually my favourite part of the game so far as it kept me on my toes and forced me to come up with strategies I would never have needed if I was just taking on mobs my own lvl. That's about as non linear as you can get.
