Notes for conventional fleet development
A conventional fleet for these purposes is one that employs both capital ships and fighters or comparable units for target multiplication. (It may or may not make much combat use of medium size units.) Baseline technologies provide the basic materials for such a fleet and won't do too well for rival fleet arrangements.
Given that basis, a conventional fleet is one of the smoothest ones to develop over time. It only requires getting techs to do better with the basic fleet roles and units you're already using. Every tech you get in this plan will make an incremental improvement – you needn't wait til you get a specific combination, or several steps down a tech line til you're able to build the fleet you want, and possibly scrap much of what you've used so far.
The conventional fleet's units fill several niches:
(1) It needs some units with large fire packets to penetrate resistant defenses.
(2) It needs units that can expect to survive many rounds of combat and be in pretty good condition afterward.
(3) It needs numerous, relatively inexpensive units to provide target multiplication – targets that will draw enemy large fire packets away from precious friendly targets, and to prevent early mass fire from bunching up on them.
(4) It needs a large number of small fire packets in burst fire early in combat to counter enemy target multiplication and to eliminate enemy fire platforms as soon as practical.
(1) and (2) are capital ship roles. (3) is for small units. (4) is at least for small units, but capital ships may share the duty or even replace them with certain tech advances.
Before enemies have resistant defenses, large numbers of small fire packets will do well for all enemy-killing purposes. This will make fighters with their cheap external ordnance racks the chief fleet unit. But that's not a long period – resistant armor is a mere Development stage, after which the enemy will have everything but cheap target multiplication units immune to 1 point fire packets (apart from their shields), and highly resistant to slightly larger fire packets. Target multiplication remains important, to frustrate those larger fire packets from falling on the somewhat expensive units mounting the resistant armor and a lot of weapons, and counter-target-multiplication remains important to frustrate that.
Better target multiplication will call for cheaper minimal units and ones that survive counters better. These considerations can pull in opposite directions – piling on defenses for surviving fire will usually make for more expense, and cheaper minimal units can be had from (e.g.) gouging maneuverability for discounts. The aim here is to make units cheaper with a minimal loss of survivability, and to make them more survivable with a minimal increase in cost. Techs for DEFENSE bonuses for fighters – or whatever alternative unit is being used, such as Hl 1 gunboats – are very good for this, as they tend not to have a fixed per-unit cost, or at least not a high one, and these units will very often not survive a hit if it connects, making Sh, Hl, and RESIST bonuses futile. FLICKER and PD are also good, when they can be had with favorable cost structure.
Burst fire is typically from missiles, and for baseline purposes prominently from fighter XO racks. Better burst fire from that starting point can come from increased fighter XO missile control, allowing them to fire more than twice hull in missiles per round; MIRV missiles; more powerful missiles with flash missile warhead to divide the damage into 1 point packets; crash racks (1 space, 1 point, fires 4 missiles in one round, once per combat); and mass launchers. Increased fighter XO missile control, crash racks, and mass launchers are each mere Development efforts. The first two will tend to keep the burst fire role in the hands of fighters or other small units; mass launchers will suggest larger units.
Large fire packets and serious survivability under continued hits require larger units. Improvements here include larger hulls; higher build rates in order to build, repair, and refit them practically; higher point per space weapons, shields, structural reinforcements; higher ablative armor caps; resistant shields and/or armor; regenerating hulls and/or shields; and various per-unit systems to increase firepower, targeting, YIELD, RESIST, FLICKER, DEFENSE, and PD values. Ways to accomplish any of these less expensively will be valuable too – for capital units, sheer power is important, but you still need to be able to afford the things and preferably more of them.
Apart from techs aimed specifically at one of these roles, players need not neglect ones that improve their combat ability overall, such as battlecomputers and ECM. They may also go for some that fill out roles for medium sized units, the sorts that you can build in a turn or less but are big enough not to wither under casual hits. Medium sized units can't take advantage of being deeply inexpensive and numerous on the one hand or of being very tough with large fire packets on the other, but the sheer convenience of building, repairing and refitting them and their utility for roles outside of main fleet combat means that you're likely to have them around the fleet anyway, and improving their role there isn't a waste. Large STL gunboats, for instance, may be large enough to survive awhile in combat, may pack fire packets large enough to penetrate some resistant defense, are discounted pleasantly for being STL, and are convenient to build, carry, refit, and repair.