I would recommend that you read
Snaaty "guide" for BTS...it has a good concept of capping your Capital early by building defenders and then rexing with settler rush and sufficient workers to bring you up to par with AI. Claim a part of the map with 7-8cities, tech toward an advance military tech...Lower difficulty try maceman cats/trebs rush higher level rifleman. Pick your weakest neighbour that’s just begging to be conquer and assimilate/vassalage his population.
You need to be patient it’s not a all type map strategy, but some tips are good for most map type...
If you have a crappy start don’t be afraid to regenerate the map, pick a strong leader Lizy with redcoats + unique building makes it’s a good civ to get use to the game mechanics, once you feel comfortable with the game you can try your luck with other civs. IMOP consider Liz like your training wheels of your first bike but for civ

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Try noble, save every ten turn if you made a big game breaking error example attacking the vassal of the strongest civ (yeah this happen to me this weekend did not check the diplo screen

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Try to remember that food=production, settle near food resources first and WORK them early; research the tech if necessary AH, Fishing etc. You can REX toward happy resource latter. Rex toward your neighbour and cut him off your backland/ressources. Look at Canada 85% of its pop is on Can/US border but still have lots of back lands (well mostly frozen ) claims on resources in the northern parts Sask, wheat, Alberta`s Oil, Ontario mineral, NWT diamond/furs, forest and wild games don’t forget NB lobster mmmm

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Plan you cities improvement, you migth want to check out the Empire Management section in the war Academy I learned a lot abouth game mechanics from these articles, Specialised your city early, establish production centers. Remember that every tile need 2 food/1pop to be worked, every 2 surplus food can count toward working a mine workshop; etc. Grasland cottage are self suficiant

When looking at a city screen I do a -food count exemple: plain hill - 2food, balance by 2 grassland farm pre biology. Try not to wast worker turns. Try to anticipate your pop caps vs workable terrain tiles with avalable ressources for happy and health caps.
If you lucky Iron or Copper will pop within your border. If not Archer are you best bet. Learned to use the wip, slavery can give you great early production advantages, bassic Idea is use slavery when in only a turn, your city pop will grow at the cost of 1 pop; Granaries are god given tools for slavery specialy in Highfood low production cities.
Plan ahead, make friend early….trade wisely and maintain a decent army and you should not be backstabs…you on the other hand can backstab your friends later hehehehe. But most importantly, have fun !