Siam: Play before patch and PTP every CS after getting consulates...nah, jokes. Go patronage and ally with as many maritime CS' as possible.
Maya: If there's room, go wide, open piety, and build your UB's ASAP. Grab messenger God pantheon too. And also try to get to theology ASAP. It's the difference between 5-6 great people anyway.
Inca: Settle near mountains, especially those hilly valley areas between mountains to make epic use of UI. Hopefully, Mt Kilamanjaro is nearby and you can rickroll your neighbours.
Brazil: get jungle pantheon ASAP, find all civs early, go tall and keep pumping out tourism. Beeline to internet and make sure you win the International Games.
France: Build all the cultural wonder civs in capitol...and surrender to your neighbours because you won't have time building musketeers whilst getting Globe Theatre, Uffizi, Sistine Chapel, Lourve and Broadway in the capitol (historical stereotypical joke). Not really recommended for higher difficulties unless your tech is superb. Rage every time you miss a culture wonder because it means your UA is less effective each time it happens.
Poland: Have a clear plan with your social policies. Your UA basically means a free policy tree throughout the course of the game.
Byzantium:leave the wide sacred sites trick to MP games because no other player would ever go for sacred sites unless they're going wide. I've had one MP game with AI Byzantium and the AI was nearly smart enough to pull off that trick. Got all 3 religious buildings, but chose Jesuit education instead.
China: Liberty/honour. UB covers gold problems, liberty covers better management of wide empires, honor amplifies UA and if filled, solves gold problems, UU and UA covers future domination.
Japan, Venice, Portugal: Restart until you get a (decent) coastline. Get Colossus ASAP.
Russia: open tradition but complete liberty, go wide, get 15% faster border expansion pantheon, build UB. Insane land grabs.
Morroco: Restart the game because I swear this UA doesn't even work, or at least it doesn't work for sea trade routes. It definitely benefits other civs with the +2
per
, but not me. Unless you're in desert mainly, UU will put you in safe hands. And obviously get Petra ASAP.
Zulus: Build up about 10 impis (obviously
after Ikanda and armory are up) and save the impis for later, upgrade them all up to mechanized infantry and go nuts. Choose shock 1, then cover 1 and 2, then shock 2 and siege to make your upgraded impis impossible to kill on flat terrain. Grab the +50% XP in Honor to speed up their development. After rifling, make sure you keep them alive.
Koreans See if you can get GL, turtle up, build heaps of GP tile improvements and...???...science profit!