That was covered in 1. Physical defense and magic defense is your lifeline. Health- adds to physical defense and increases your HP. Int - ads to magic defense.
Items you need to help raise these were covered in 2. Rings and armor upgrading is very important because the higher you upgrade these items (red war gold) the better the bonuses for physical and magic defense they will give. Rings magic defense. Helms, boots, gloves, armor, leggings defense.
If you are not satisfied with your stats, the Cash Shop has stat resets and items to boost certain stats. The Goods Merchants located in each town also have scrolls that can increase certain stats for short periods of time though they can become costly if used habitually.
If there is a white mage leveling (redwar gold) near you or grouped with you, do not forget buffs can also help. Unfortunately, yet fortunately, we are usually a solo player and depend on what your class has to offer, so you are not a nuisance to other players by asking for buffs constantly.