Well I started on normal and game is kicking my butt. Haven't died yet but were close quite a few times. It takes like a full combo to kill a normal enemy... whats up with that?
Oh and those mini bosses mess me up like I was a tooth fairy and not War
In that case, my other tips would be learn to LOVE your dodge button. LOVE IT.
Also, learn to strategically use your lock-on feature. Sometimes, it's best to NOT lock-on to the enemy you want to fight, simply because it allows you to switch up your attack direction on the fly.
Side dashing > back dashing - you can chain side dashes. You cannot chain forward/back dashes.
Don't ever forget that you have the geyser attack (the one that uses rage or whatever it's called). It's a life saver and quite strong, even at level 1.
Buy sword moves. I don't have any in particular that I use more than another, but buy them. They're all great and provide excellent options in combos (the ability to knock an enemy up, back slash the guys behind you, followed by dash piercing some other guys next to you is great). Oh, and they look flashy.
One thing I learned playing Apocalyptic - sometimes it's OK to sacrifice yourself to get full health back, haha.