Here's what I do for my starting configuration.
It works for all difficulty it seems. I'll fill up all my main cannons with the Energy Cannon and max out their recharge time, which translate to 0.4s and spam the hell out of my enemies.
Small ships go down fast, larger ships go down slower but it does the job. I only upgrade the recharge time and once I get enough scraps, i fill the defense with either Gatling or Bolter.
I'll get 2 more Carrier or Destroyer and fill their main with Nukes or Missiles.
Attack strategy is to stay away from enemies battlestation or warp right in the middle of the ship's position.
