I just started playing the campaign tutorial and I must say that maybe when I finish it I could have a sort of routine I could follow for every game that I would be having. I must say that things are really pretty hectic despite the game being a tutorial and the frequent ai attacks (not waves) which sends a couple of missile frigates,bombers and fighters is annoying since they usually target my tractor beams and that warp sensor thing (the thing which indicates the wormhole that waves would come from).
Sounds like you want to build more turrets. On a map like that with not too many fronts (I think the most border planets you can have is two, right?), I'd recommend building enough defensive emplacements that in a normal wave nothing makes it away from the tractors alive. That should take care of border aggression pretty easily.