Going to work with the idea of T3 Frigates first because they would be cheaper, faster to train and get less whining than Cruisers, BCs or BSes.
First of all you would pick a slot configuration (all have 3 rigs):
- 2 low, 6 med, 3 high
- 3 low, 5 med, 4 high
- 4 low, 4 med, 5 high
- 5 low, 3 med, 4 high
- 6 low, 2 med, 3 high
Then you chose a hull bonus by popping in a sub-system:
- 15% bonus to Shield / Armour Transporter boost amount, capacitor use 700% bonus to range (vs 10% and 500% for T1)
15% dmg, 10% tracking, 15% optimal, -65% MWD sig penalty (vs 5% dmg,
7.5 tracking, 10% optimal, 5% dmg, -50% MWD sig penalty for T2)
.... you get the general idea.
Now, here is one of the keys to this - the base stats remain almost the same as T2 frigates (hull, armour, shields, resists, speeds, etc)
This means that it comes down to how you link your slot configuration + subsystem bonus + modules fit.