Do you really need crib notes to be a ninja? In two cases, no: 1) you know by heart all NPC damage types and resistances, as well as the natural resistances of all missioning player ships, including Tech 2 and Tech 3 ships; or 2) you fly a Harbinger and you can't change your damage types anyway. In all other cases, it's helpful to have some quick reference notes by your side. Hunting someone in Angel Extravaganza? About to engage a Vargur in a Blood Raiders deadspace? What ammo should you use in your Hurricane or Sacrilege?
When I was starting down the ninja path, I knew I would need quick answers to those questions, so I cobbled together a list of the tanks I would be facing in Lonetrek...
Marauders Tank Type Weakness Golem shield EM Kronos armor Exp Paladin armor Therm (or Kin) Vargur shield Therm (or Kin) T3 Cruisers Tank Type Weakness Legion armor Therm (or EM) Loki either Kin (or Exp) Proteus armor Exp Tengu shield EM Mission Name Player Tank* Player Ammo* Angel Gist Kin/Exp Exp Blood Corp EM/Therm Therm Drone omni EM EoM Kin/Therm Kin Gallente Kin/Therm Kin Guristas Pith Kin/Therm Kin Mercenaries omni (K/T) Therm Sansha Cent EM/Therm EM Serpentis Core Kin/Therm Kin
*refers to the player running the mission (my target), not the NPCs
In general, someone in Angel Extravaganza will be tanked against Kinetic and Explosive damage, and they will probably be dealing Explosive damage. A Vargur has a natural Thermal weakness, but a Vargur in a Blood Raiders mission will probably have plugged that hole, so shoot Kinetic at him instead.
Choosing damage types is an essential part of PVP in EVE, right up there with aggression timers and transversal velocity. It becomes even more important for solo PVP, since you usually become the main source of damage. Want to double or triple your effective DPS? Choose the right damage type! I've discussed it in previous posts if you want real examples.
It's also worth pointing out that these lists can only help you guess what you'll be facing. Fit a Ship Scanner if you want to be sure. It's always possible you'll run across an omni-tanked missioner.

