Hi!
scout ship
I don't use scouts. All scouting is done by my colonizers. Only they can be fast and with good range, and can actually take the planet for me. The only thing that could be referred as scout are my anomaly explorers: cargo hull, survey module, 3-4 engines, rest life supports, but those are after-colony-rush ships.
heavy fighter
I don't build small-hull based ships. I fight with mediums. Only in them I can fit enough equipment to made them usefull. Yes, my early game military is virtualy non-existent. Only after AIs start threatening I build some fake defenders: cargo hull with single cheapest beam, missile and mass weapon. In orbit it shows attack 6, thus increasing my military score considerably for quite low price.
light fighter
I use a "sensor": cargo-based hull with single Laser5, 3-4 Ion engines, maybe 1 life support, rest sensors. Mid-game item, small number built. Watches my space for unescorted troop transports, accompanies my first warfleets as armed scout/interceptor, kills unarmed ships / SBs / miners of my enemy.
Troop transport
2 best troop modules, 3-5 engines, nothing else. I want their price low, as I'm going to build them in quite large numbers.
I'm NOT using ANY life-supports in my warships and troop transports. I extend the range of my warships with building an economy starbase right in the middle of the planets I intend to take. Once they're mine, I already have a SB there to boost their production.
BR, Iztok