Whenever you kill an enemy and their carcass falls to the ground a strange light will sometimes emit from it. This means that it has items that you can collect.
Enemies
When you encounter enemies that are a much lower level than you you will often find that they will ignore your presence while enemies that are of similar or higher level than you will automatically attack you when you come in range.
Split Bombs
These bombs are very effective when you need to hit multiple targets that are separated by small gaps.