Howdy everyone, first post ever here.
Thought starting a thread where we could share some advanced tips and such. I will start. (version 1.2) Correct me if i'm wrong(as if you need my consent).
Income - City center doubles the tax generation in the region. So even if playing conquest game a player should build at least one more city center due to extra tax income it generates through doubling of income(through taxes) in that region. The longer the game, the more are justified to build.
Income generation per population is not linear, the gain of income diminishes the more population the region has. Hence, it is profitable to build more smaller colonies, cause the same amount of population distributed through regions generate more income(except regions with city centers, those should be always near maximum).
Some races exacerbate income problems, such as ch'cht, so even building a farm first to get some wood for housing and cultural center is justified. 20 extra credits for a simple housing building is noticeable for ch'cht, especially when first 100 colonists give only 8 credits, compared to humans, who give 16.
Income, morale and culture - This one is my favourite. Let's start with simple stuff. A region with city center with bigger populations should use bigger tax rate than other regions. It is more profitable to put workers on culture in city center than on trade, if the tax rate can be increased.
Culture generation doesn't follow the classical rules of resource generation. In interturn order(i borrow that terminology from civilization 3), it is somewhat last. Example: A cultural center is being built in the region on turn 10. Two workers are building it and on turn 11 it should be operational. What is being hidden is that after the building is built inbetween the turn 10-11, the workers are placed automatically on generation of culture and on that same turn they generate +4 morale(2 each) for the turn 11. This can be exploited by setting the tax rate higher by one degree on turn 10(the workers are still building the cultural center), hence the morale should drop by 5. Due to the interturn mechanics, on turn 11 the morale drops by only 1 point(+4-5), hence generating the extra income for turn 11. This can be used even more: If there are extra workers lying around doing nothing, 2 more workers can be dropped on to the cultural center, which is being built on turn 10. It will generate +8 morale for turn 11, hence even bigger tax increase can be used(or lost morale reclaimed).
The same trick(with bigger gains) can be used when upgrading cultural centers to museums. Example: On turn 13 there are 4 workers on a cultural center and it should be upgraded by turn 14. Inbetween the turns the building is upgraded to museum and extra worker is put on housing. The three remaining workers are automatically put on generating culture, thus raising the morale by +15(+5 x 3) for the turn 14. Thus it is advisable to start reducing the morale by 5(one degree of tax increase) from turn 12, thus the morale is 95 by turn 13(this doesn't incur any penalty). Then it is advisable to increase the tax rate for that region even further, thus the morale drop should be -10. Classically, the morale should drop to 85 on turn 14, but because of the interturn mechanics of culture generation, the morale will hop to 100(95-10+15). This also makes putting extra workers on culture in cultural centers one turn before upgrade useless, cause the culture/morale is generated after the building is upgraded. These calculations don't include other bonuses nor penalties, so be advised. And of course cyth can never use this trick.