Here're a couple tips for a beginners:

The thief ring is invaluable.
A bow can be your best friend, don't be afraid to snipe!
You can cheese your way through anything with poison cloud.
Being quick and avoiding damage completely is better than bulking up your actual armor.

Once you learn your enemies' attacks you can manipulate your health using certain items and take advantage the Clever Rats Ring to mop the floor with them.