Belt Rats

Damage types to protect against

• Guristas - Kinetic & Thermal
  
• Serpentis - Thermal & Kinetic
  
• Mordus - Kinetic & Thermal
  
• Blood - EM & Thermal
  
• Sansha - EM & Thermal
  
• Angel - Kinetic, EM, Thermal & Explosive
  
• Mercenary - Kinetic, EM, Thermal & Explosive
  
  

Damage type to shoot at the enemy

• Guristas - Kinetic
  
• Serpentis - Thermal
  
• Mordus - Thermal & Kinetic
  
• Blood - Thermal
  
• Sansha - Thermal
  
• Angel - Explosive
  
• Mercenary - Thermal
  
  

Warp Scrambling NPCs

NPCs that can warp scramble your ship and prevent it from warping out of the belt will have the following words as part of their name. Watch out for such spawns. Sometimes it is better to just let them be and wait until they despawn rather than engage them. These NPCs are also capable of using other types of electronic warfare, such as webifying or jamming.
Guristas - Dire
Sanshas - Loyal
Serpentis - Guardian
Blood Raiders - Elder
Angels - Arch angel

Faction Spawns

NPCs with the following indicator names are faction spawns. They might drop faction items or tech II implants some of which are worth a few hundred million. A faction spawn is not guaranteed to drop any faction items.
Guristas - Dread Gurista
Sanshas - Loyal
Serpentis - Shadow Serpentis
Blood Raiders - Dark Blood
Angels - Domination

Officer Spawns

Officer rats are a very rare find. They drop officer items that can be worth anywhere from a few hundred million up to a few billion ISK. These are listed starting with the most common officer and ending with the least common and most prized one.
Guristas - Kaikka, Thon, Vepas, Estamel
Sanshas - Brokara, Selynne, Vizan, Chelm
Serpentis - Brynn, Tuvan, Setele, Cormack
Blood Raiders - Tairei, Raysere, Ahremen, Draclira
Angels - Mizuro, Hakim, Gotan, Tobias