also u dont need to win every mission in order to continue playing the campaign, so if your stuck on one and cant seem to win just retire and hopefully the next one will be easier (of course you can do this too many times in a row and you cant do this on the last mission otherwise you will lose)

My advice would be to crank up the difficulty level (the converse of what you would expect, but, as stated above, it helps your allies quite a lot and doesn't really affect the Dread Lords, since they can already kill everybody without help), build swarms of fighters with as many weaponas as you can fit. I wouldn't bother with defenses, because even with a massive hull with maximum miniturization it isn't possible to get the level of shielding required to stave off their attacks and remain offensively competitive.
If you are feeling adventurous, negelct researching the better hulls entirely and instead stock up on miniturization, logistical, and mass-driver technology, then mass-produce fighter fleets with Black Hole Guns (or go for the Evil alignment, and pile on Psyionic Guns or whatever they're called).
Make sure to guard your transports - they are especially vulnearable when ships with +14 parasecs/week can zoom in, blast them, and zoom off before you can react.