Concerning diplomacy with the AI.
Send Pirates when you can afford them, to your next victim, or perhaps 2 victims down the road. Don't bid up slowly. Bid all at once > 1500 ( < 1 hour). So don't bid 500 when you can only add another 500. You'll get furry pirates on your doorstep before your defenses are set, or at best you'll get a bounty without the actual raid, if you manage to outbid, 250 at a time. So don't do that.
Don't give metal, crystal, or cash, to anyone, unless you're wealthy and really can't use the resources, or need to beef up a failing ally. So, don't concern yourself with the early missions from the local thugs. Show them your unimpressed scout, running circles around their frigates. They'll forget soon enough and come back begging with something more palatable.
Attack one enemy at a time. Whittle them down. Take a planet at a time. Anytime after you start approaching an AI empire, the other empires will start offering you missions to do just what you are going to do anyways: Pound their shiny infrastructure into spacedust. You can practically ignore the diplomacy screen and build up decent relations with most AI proceeding this way. Soon you'll get requests for trade alliances, cease-fires, and even peace treaties. Accept them all, unless they are your next victim. Don't worry about the idiotic trade ships getting killed by wandering into battlefields. Just forget all about them. You'll make money, and more importantly, keep the AI off your back indefinitely.
The more AI, the better. With 9 you'll often get 3-5 identical missions to "destroy 2 civic structures of that poor slob you are currently annihilating, m'kay?". So, a few minutes later you'll be getting a deposit of 2400-4000 credits, and an armada of crystal and metal deliveries.
If you either use the pirates or play the diplomacy game (which is just a massive incentive to proceed logically, taking on one empire at a time), you'll find the game much easier. Use them both and you'll be bored of wiping out nearly uninhabited systems, pre-cleared by the local mercenaries. Personally I don't use the pirates because it makes the game too easy. I let the other empires duke it out, and if they put bounty on me, I just put bountyx10 on a random one of them, or take the raid as a test of my chokepoint defenses (mid-late game).
I hope these 2 game aspects get tweaked in the future. But for now, I hope this makes things easier for those who are having those "Why are 8 AI empires attacking me?" kind of problems.
