Hi Apophis! Some thoughts in response to your last post:
I would definitely say that this game just gets better and better the more you play
On not learning from mistakes, if you don't start on too high of a difficulty, (I started on 6/6 after reading lots of stuff, like you did), the strategic sort of mistakes probably won't kill you. But it doesn't mean you can't learn from them. Every little hole you leave in your position tends to become a Chekhov's Gun in this game, but on a low difficulty, it's not going to kill you outright, it's just going to point out that maybe leaving this mark IV planet nearby wasn't a good idea (as it proceeds to build up to epic proportions), or maybe that going out of your way to capture that fabricator wasn't worth (as it gets wiped out by a cross-planet attack). The lessons to learn will be there, and once you've played a bit, it'll be easier to spot the difference between the things you and someone else are doing and learn from them.
Also, what zharmad said: as long as you're getting something out of the AIP you're paying, it will be fine, that is the purpose of AIP. So experiment, by all means
On capturing systems: you can surely split those into offensive aka. getting goodies and as "stepping stones", and you may or may not want to hold these systems, as Wanderer pointed out, and defensive, which create a buffer before your homeworld or strengthen your defense in other ways, such as decreasing your surface area. Thing is, you can achieve your defensive goals via neutering to some degree, allowing you to spend more of your "AIP budget" on offense (since a neuter usually costs you 5-6 AIP at most). Of course, there are planets which can fulfill both roles, and those are the planets you'll probably want to build your strategy around.
Lastly, if you want to talk some strategy, you can find me on skype (I'll PM you the details). I'd love to help, maybe we can even fire up a game together