I've played through several games of this and I've been having a really tough time of it. I must be doing something wrong because by the mid to late game I'm falling into slow ruin. My populace is unhappy and my deficit is through the roof so research stops, which puts me even further behind, and at that point I'm just trying to stave off the inevitable.
Even on normal the AI is pretty decent. It seems like they always go for the one aspect of my civ that I was neglecting. If I try to out-tech them, they attack. If I try to attack, they manage to hold me off long enough to out-tech me. If I'm turtling, they wear me down slowly. If I'm moving quickly they invade planets while my attention is on something else.
I've watched the tutorials, so I have no idea what I'm doing wrong. Usually the first few things I do are colonize any planets I actually have a chance at colonizing, then specialize one planet in research, one in industry, and one in economy, if I have three. Then as soon as I can reasonably get a constructor out I build a military starbase next to my original colony. After that I'm mainly just teching up and building ships.
I guess I just don't know how to make my strategy come together.