The best advice I can give you is this: adopt a very defensive play style for your first time through the game. Find the Purple Flame Shield on 1-1. Find the Winged Spear on 1-2. Proceed to play turtle, poking with your spear while you block with your shield. Oh, and ditch most of your armor so you can "fast-roll", because dodging is about 10x more effective than blocking. Just make sure you're fighting in a decently open area. You don't want to be fighting in narrow hallways or on the edge of a cliff if you can help it; failed rolls will kill you more often than anything else.
Once you're relatively comfortable with the rhythm of combat, start paying attention to vulnerabilities. Some enemies are vulnerable to piercing attacks, which your spear covers nicely. Some enemies call for magic or fire. Others will be knocked down and subsequently owned by heavy weaponry. Using the wrong weapon is like fist-fighting a dump truck, so expand your arsenal whenever you can. Oh, and try to find a bow as quickly as possible. They're the only ranged weapons you can actually aim for long distance shots, which is crucial for pulling enemies into more favorable environments.