Main resists to use:

Angel: exp / kin
Amarr Navy: EM / thermal.
Ammatar Navy: EM/thermal.
Blood: EM / thermal.
Caldari Navy: Kinetic / thermal.
Centii: EM / thermal.
Coreli: Kinetic / thermal.
Corpii: EM / thermal.
Domination: kinetic / explosive.
Gallente Navy: EM / thermal.
Gist: kinetic / explosive.
Gurista: Kinetic / thermal.
Khanid: EM / thermal.
Mercenary: All types.
Mordus: Kinetic / thermal.
Odamian: Kinetic / thermal.
Pith: Kinetic / thermal.
Rogue drones: exp / kin
Republic fleet: kinetic / explosive.
Sansha: EM / thermal.
Serpentis: Kinetic / thermal.

Main Damage types to use on npc factions:

Guristas - Kinetic
Serpentis - Thermal
Mordus - Thermal & Kinetic
Blood - EM & Thermal
Sansha - EM & Thermal
Angel - Explosive
Mercenary - Thermal
Corpum - EM & Thermal
Gist - Explosive