Most of us are aware that the purple stars have a higher influence than the yellow stars (yellow stars have an base influence value of 10 - 14). Earth has a base influence of 20.
But I guess that only a few know that there are often some planets with very high base influence value (I think up to 60).
When you have unfolded the map and have a solid economic basis (you need to invest a few thousand bc), go to the planet list (F2) and choose stars. Then sort for influence. Now check all not yet occupied stars at the top of the list and check them for usable planets.
It depends which mods you use what you can get to 15 PQ. I usually colonize down to PQ 9 planets.
Build a starbase full with production boosters and then culture boosters in this sector and get all the PQ, moral and culture boosters facilities on this planet (in this order). It might be necessary to rush buy Entertainment Network despite of the costs to avoid moral issues. I usually buy the Fusion Power Plant, too to speed up the build.
The values you get are much higher than what you can ever get on Earth or somewhere else.
When you are lucky and find this kind of treasure near by an alien it often can cause a domino like takeover of a hughe sector of the galaxy