A few ones I like to do:
- role playing as much as possible. Includes building that wonder a civ is known for, as has been mentioned. So beeline it whenever possible, that wonder is 'yours', you must have it.
- always found a religion for 'religious' civs, even when not going for that route. And once you have a religion, make sure all your cities have it
- not too strict on chops, but I like the old lumber mill rule. So never chop a woods/rainforests along rivers, not even for a seemingly irresistible district (or districts).
For those not next to rivers, you can chop once to rush something you need yesterday, otherwise no strategic chopping. Only do it if you need the space for something (or removing rainforests for appeal).
- do not use Reyna/Moksha to buy districts.
- no switching out techs/civics. If your civilisation cannot eureka/inspire it, then just hard research it. If they can, it becomes a fascinating race of trying to achieve it before you finish the research, like internal factions competing for ways of discovering tech/civics
- if going peaceful, no pillaging. If warring, never declare peace! And only pillage for healing and traders.
In a peaceful game, only loyalty flipping is allowed. If at war and then you declare peace, you can never enter that territory for battle/pillaging again. Exception exists for 'revenge'.
- aesthetics: I never build spaceports next to the city centre. I love the idea of farmers looking up and seeing a space launch. Airports must also be as far away from other worked tiles as possible. I view industrial zones next to Holy Sites as 'clashing'; sites must be in a serene region for meditation