[dmm]

When starting with low tech, here's how to get a good early fleet:

1) Research armor to level III.
2) Make large numbers of escorts with nothing but required stuff, 6 engines, and armor.
3) In battle, use them as rammers.
4) A few ships with DUCs will act as lures for AI fire, causing unarmed rammers to be ignored.
5) If you don't have armor yet, use transports or even colony ships.

So far, this fleet is only good for defense. So,

6) Research frigate and repair, and make some repair ships to accompany your hordes of ramming escorts.
7) Start building ramming frigates with a weapon or two for attacking planets.

This early strategy should buy you time to research some good long-term stuff, like boarding parties, troops, special racial techs, proper weapons, etc.