Generally there are six types of PVP pilot - you're not restricted to picking one:
1. High DPS pilots
2. ECM pilots
3. Tackler/Interdictor pilots
4. Gang/Leadership pilots
5. Sniper Battleship Pilots
6. Scout
There are others - capital ship pilots, logistics and 'priest' ship pilots, but this is a start.
What do these roles break out as?
High DPS Pilots
Role: Alpha strike with near instant damage (hybrids, lasers, projectiles) or high DPS with delayed damage missiles. Offense is your tank.
Direction: Aim to fly a HAC, Battleship or BC. Focus on DPS mods and rigs, light tank
Ship Skills: Heavy Assault Cruiser V, Battleship V, Battlecruiser V
Skills: Weapon Upgrades V, Heavy Assault Missiles V, Medium or Large Hybrid/Projectile/Laser V (Med for HAC, Large for BS),
Torpedo Specialisation IV, Advanced Weapon Upgrades IV
ECM pilots
Role: Target negation, jamming means that remote targets will lose locks. Denial of targeting is your tank.
Direction: Start in a blackbird, progress to a Scorpion, then move to Falcon
Ship Skills: Caldari Cruiser V, Caldari Battleship V, Recon Ships IV (V is a 33d train that XorX is currently going through)
Skills: Electronic Counter Measures (ECM) V, Long Distance Jamming IV, Frequency Modulation IV, Signature Focusing IV, Long Range Targeting IV
Tackler / Interdictor Pilots
Role: Get points on the target to stop them getting away, then just chip away at them to get on killmails. Speed is your tank.
Direction: Start in a frigate, move to interceptor, then interdictor and finally heavy interdictor.
Ship Skills: Frigate V, Interceptors IV, Destroyers V, Interdictors IV,
Skills: Propulsion Jamming V, Afterburner IV
Gang / Leadership Pilots
Role: Provide bonuses to the fleet as well as well-tanked DPS. You will often be called primary, so tank well.
Direction: Start in a battlecruiser, move to Command Ship
Ship Skills: Battlecruiser V, Command Ships V
Skills: Leadership V, Wing Command V, All the warfare and linking skills V
Sniper Battleship Pilots
Role: 150KM+ sniping of targets. Instantaneous mass damage to a single target called by the fleet commander. Distance is your tank.
Direction: Start with T1 Battleships, move to T2 battleships or sniping HACs.
Ship Skills: Battleship V (All races have a sniper platform - though the Rokh (Caldari) is probably best)
Skills: Large (Hybrid | Projectile | Energy) Turret V ; Appropriate Hybrid / Projectile / Energy Turret Specialisation IV ;
Long Range Targeting IV; Advanced Weapon Upgrades Advanced Weapon Upgrades IV ; Controlled Bursts IV ;
Motion Prediction IV ; Rapid Firing IV ; Sharpshooter IV; Trajectory Analysis IV; Weapon Upgrades V; Surgical Strike IV
Scout
Role: Advance of fleet searching, scanning safespotted enemies, providing warp-ins for the fleet to surprise enemy. Also generate cyno fields for moving capitals etc.
Direction: Start with T1 fast ships, then move to Covert Ops and then Recon Ships. Warping when cloaked is the key. Cloaking is your tank. Requires a lot of patience, the ability to work fast when a target is found, and no desire to be on killmails (although later on, Recon ships are a deadly scout).
Ship Skills: Frigate V, Covert Ops Ships IV, Recon Ships IV
Skills: Cloaking IV, Astrometrics V, Survey IV, Astrometric Triangulation IV, Astrometric Pinpointing IV, Signal Acquisition IV,
Cynosural Field Theory I