One important strategy that it seems many people do not realize is concentrating on a few (or just one) key worlds and focus everything on them. After playing quite a few games with Intrigue I'm even convinced now that the most effective strategy is to focus everything on ONLY your homeworld for at least the first 150 turns.
If you are playing on the higher difficulties you absolutely should try this out one day. It enables me to dominate a game on Genius difficulty pretty much from the beginning.
What do I mean by 'focusing'?
- build a city on HW as soon as you have 4 Food available
- max your HW's population ASAP using Colonial Hospital and/or by ferrying pop from other planets to it (gets Raw Production up)
- to get the morale needed for that use improvements, mercs, techs, Celebrities (you get 2 of those for free for researching approval techs)
- whenever you have some spare cash build asteroid mines in your ZOC and assign them to your HW (again, to get Raw Production up)
- assign all your Scientists and Engineers to your HW as soon as you get them
- IMPORTANT: build economic starbases around HW as soon as they appear reasonable (e.g. once you have researched the first two manufacturing and financial starbase improvements)
- research the Life Support techs that each give +2 to starbase radius and build even more econ starbases around HW
- look out for planet-boosting mercs and government ships and put them in HW orbit
- research the governance tech line (up to Star Federation) for it's bonuses to Raw Production
To give you an idea of what an effect this has, this is my HW from a typical game of mine at turn 100 (note the Raw Production and planetary output):
And here at turn 150:
Race was Vigilant Conquerors btw.