Ship weapon loadout

[oogs]

I'm rather new to the game... still playing the demo. One thing that is still eluding me after several 100-turn runs is the optimal weapon load for a ship.

I have tried several things:
-All DF weapons (maxing out the demo's tech level), but these failed miserably vs the AI's missile ships.
-All missiles, which has enabled me to play ~50 turns w/o loosing a ship and winning every battle... that is, untill I tried shooting down satelites.
-A mix of the two, but that is a bit more complicated.


In my current game I am using the all missile ships, and I have integrated light carriers (I'm researching carries now). My missile ships - while great at dealing with enemy ships - cannot touch satellites or fighters. They are great because I can pretty much ignore defense and equip them with as many engines and missiles as possible, so they get in firing range, fire 7-8 missles each, then run away for a couple turns.
The reason I stopped using all DF ships was beacuse they needed to be fast, have lots of weapons AND lots of defense (so they can withstand any pounding that occurs before/while they are in range). This is also what is making me hesitate using a mix of DF and missiles.
Is there any sort of general rule when it comes to outfitting ships, or do you have any suggestions for how I should try to outfit my ships (keep in mind that the demo doesn't let you get above cruisers).