My advice? Slow down research (and thus the game). Forget victory conditions (make sure they never trigger, either by 100% requirement or very long minimum time (not sure if time is possible). Disable story lines. Smell the roses with no stress of artificial time limits or pesky refugees. Reducing home world qualities should also slow down the early game further.
The key in designs is enough energy to fire guns and cruise at the same time. When it comes to components, I don't find it too bad, but I got no mini-max source.
Different lines of tech (where alternatives) got different benefits. I don't think it is too hard to get the hang on choices for tech. Pay notice to the trends. I don't have the game open, and don't know tech by heart, but I think energy is like:
One shield line has more strength, another recharge faster.
One reactor line has more beef, look for reactor size and fuel economy on the other, and how upgrades look. If you design yourself, maybe split fighting and non-fighting ships on fuel to spread the need?
Hyper drives are those using little fuel, those "jumping" fast, and those travelling fast. What do you prefer?
Engines have efficiency vs power, I think.