"Siege units inherently start with promotions that reduce incoming range damage, typically making them a better option for coastline defense than traditional ranged units."
"Promotions that indirectly give extra movement (like Woodsman moving through forest more quickly) are active as soon as they are chosen. Use a timely promotion to escape a sticky situation!"
"The yields from natural wonders are typically most impactful at the beginning of the game, before cities have infrastructure and tile improvements. Settle cities with access to them as soon as you can!"
"There is a diplomatic penalty to steal land using a great general, but not when at war with that person."
"The heal ability of the great admiral completely heals units stacked with and surrounding the great admiral. This includes embarked land units."
"Invest in wonders only if when doing so they will be completed by the beginning of your next turn to minimize the chance of losing the investment if the wonder is built by a rival first."
"To bypass defense pact blocs, you can attempt to make your target declare war on you instead. Annoy them as much as possible through diplomatic means, such as denouncement and making demands!"
"With the right promotions, scout units can be specialized to slip behind an enemy's frontline and wreak havoc by pillaging tiles, roads and trade routes. Your rival can't reinforce their army with empty coffers!"
"Scout units get a damage bonus when attacking siege units."
"When a city is captured, the garrison unit is destroyed. Capture cities with units you can afford to lose on a potential counter-capture, or use a unit that can move after attacking to take a non-secure city."
"If a melee unit would deal enough damage to capture a city, the unit's HP will always be reduced to 1 if the attack would have otherwise killed it."
"While certain civilizations have victory paths that fit the abilities of the Civ, also consider how your rivals are trying to win. A victory condition with less competition can be easier to complete."
"Great admirals and great generals apply a slight combat bonus to city defenses when that city is within their buff radius."
"Winning offensive wars quickly is paramount to keeping your happiness high and enemy resistance low. A successful tactician knows when to sacrifice a few pawns to take the queen."
"When founding coastal cities, remember that a fewer number of immediate surrounding coastal tiles makes naval invasions less problematic. Be prepared to need a navy to defend cities widely exposed to the ocean."
"When electing a host for the world congress, even if you don't have enough votes to elect yourself, good AI friends may vote for you as leader if it would suit their interest."
"The amount of diplomatic goodwill you receive for helping to pass another civ's proposal is proportionate to the number of delegates you contributed to passing it."
"Typically, you should only trade for luxuries you need to keep happiness at acceptable levels, instead of all that are available. This makes it easier to later trade for luxuries to satisfy a city state quest or We Love the King Day request."
"Before archaeologists become available, consider denying open border requests with untrustworthy rivals. They may otherwise dig up your artifacts!"
"When at war, baiting the AI to capture an allied city state that is protected by other civs is a good way to turn the world against them!"
"Even if a rival is too distant to invade, you can still slow them down with war without capturing a single one of their cities. Capture their city state allies and pillage their trade routes in neutral territories to strike a blow."