Sid Meier's Civilization V

• The AI is hard-coded to declare war on you, sooner or later, if you expand into "their" territory. This generally means that if you see something nice next to them and settle to claim it, you'll have trouble later. It's similar to how in vanilla Civ 4, a civilization with a different religion was destined to one day hate you so much they'd go to war, guaranteed. If you're afraid of stepping on toes, go for a compact Civilization rather than trying to set up borders as far as you can get away with.

• Combine this with the fact that the AI is really bad at breaking through a strong choke-point(mountains!) and the fact that eventually they will throw gifts at you to end a losing war(emphasis on eventually, decline bad or neutral offers until it happens) and this can be profitable.

• If you are afraid of losing wars and getting pushed around, play China and keep a Great General around for his ability to generate a Citadel. With proper unit cover, a Citadel will never be dislodged by anything a computer player can do in early warfare, where you've got the most to fear from a too-strong early bully.

• You don't need to build roads to connect resources!

• And if you want to immediately ruin any sense of balance among leaders and spoil the game for yourself, play as Alexander and butter up as many city-states as you can. Your Civilization will accelerate wildly after the first few food or culture bonuses. Combo this with the City State Diplomacy mod and you'll forget what it's like to lose. Also amazing to see somebody start a war with you and get savagely reamed by your 7 best friends.

• City State Diplomacy is itself a pretty great mod though, bringing back the sort of Diplomat units from Civ 4 that seem to have gone missing.

• Pick one of the victory types and aim for it from the beginning. If you're going for cultural victory, for example, your policies/techs/city specialties will be very different than if you were going for military victory.

• If you are playing on any difficulty above Chieftain, a military is a necessary evil and even if you never have to use it, you need to have it just so the AI won't smell weakness and invade. Butter up some militaristic city states nearby, if you don't want to divert your cities' attention to producing units.

• If you have Gods & Kings, don't underestimate religion. You can get some pretty awesome perks from it.

• You should settle your cities around as many luxury resources as possible, and away from resource-barren tiles like deserts and tundra.

• Scout as much as possible at the start of a new game. You can find ancient ruins which upgrade your units & cities, City-States who have unique resources, and other Civs who will be valuable trading partners.

• City-states will give you gold the first time you meet them: 30 gold if you were the first Civ to meet them, and 15 gold if you were not the first.

• Barbarian camps cannot spawn on a tile that you are able to see. If you find yourself with extra units, consider placing them on tiles outside your city borders to prevent barbarians from spawning close to you.