I fly Tracking Disruption for Amarrian fleets. It’s an interesting role - and well applied E-war is a massive force multiplier in an appropriate fleet.
So, what have I learnt?
You can soft kill a target - rendering it almost completely impotent. I can cut optimal on a target by 80-90% or degrade their tracking to the point of irrelevance.
Sensor damping can do similar: tangling a target in a mess of locking and unlocking targets. Very slowly locking. And at best you’ll be a minor entry on a kill mail.
It’s not a role for glory.
You will not be in the main fleet - you’ll act reasonably independently in many fleets. You’ll stand off from the fight applying your magic. I engage at 80-100km in a Crucifier. Watch ships closing on you; you will be paper thin and unarmed. Speed and awareness are your friends here.
Frigates are often as effective as cruisers. The skill barrier to starting E-war support is very low, but the specialisations; which increase the strength of E-war effects are very powerful.
Learn what the capabilities of enemy ships are - which are most impacted by your choice of E-war (or what your FC has asked you to bring). For example, using Tracking Disruption on a Caracal is pointless as it is a missile ship. Use Missile Disruption instead.
Understand priorities. Remote Sensor suppression of logistics; either to break locks or cause a very long lock time can be devastating. But be aware of how your enemy reacts to it - most E-war has counters (sensor boosters, tracking computers and so forth).
The best indicator that you are effective is not the praise of your FC (he’s too busy) but when the enemy deliberately makes a definite attempt to kill you. Then you know you are hurting them. Warp away, bounce off a safe or a celestial and come back in. Keep shaking them, keep them chasing you. You are helping your fleet do its job.
Tracking Disruption - evil. I like de-fanging an opponent. But it takes knowledge of good targets to apply it to.
Sensor Damping - evil. I like to frustrate any support that an enemy ship is getting. Needs a good knowledge of the sensor and targeting mechanics and to recognise when you have hurt a target so you can switch to others.
ECM. The old favourite. It stops anyone targeting anyone but you. You will be attacked, but for a short, glorious moment you’ll have crippled someone.
Target Painting - I understand it, but probably don’t appreciate it as much as I should.
Also: look at tackling roles: fast ships with a mix of earn disruptors and scramblers with webifiers as well. Grabbing targets for the fleet to kill. An exciting activity and often valued.
And good logistics pilots are always valuable - remote shield boosting and armour repair to keep your fleet fighting. An FC will rarely turn down a competent logistics wing.