@Panzerking
It should be a part of your strategy to eliminate your strongest rival BEFORE they can build nukes.
I prefer the spy war: Bribing the rival's cities.
I usually do this in several steps
Step 1: Expansion Part 1 - Target: Monarchy
Wonders: Hanging Gardens, Colossus, Marco Polo's
It's important to build 2-4 triremes with diplos on it in order to
discover the world an find advanced tribes.
You should have cities in the neighborhood of each civ.
Step 2: Expansion Part 2 - Target: Republic
Wonders: Michelangelo's, Leo's, Copernicus, Sun Tzu's(!)
Step 3: Expansion Part 3 - Target: Democracy
Wonders: Bach's, Statue of Liberty, Newton's
Nice to have: Adam Smith's (but no must have at this moment)
Step 4: Expansion Part 4 - Target: Industrialization
Wonders: Darwin's, United Nations, Hoover Dam, Cure for Cancer (!)
During step 1-4 I try to avoid war.
Why no pyramids? Because I will bribe the AI city that has built it
The wonders that I mentioned are a must have.
Every city must have a temple, and, if possible, a market place.
Some frontier cities will get city walls.
At this point of the game I usually have abou 30-50 cities (that depends
on the size of my home continent)
Now I'm ready for war.
Step 5: Fundamentalism
Since I have temples and market places in nearly all my cities, Fundy brings me
a lot of cash. Most of the cities celebrate (Mike's+Bach's+CFC !!! = ca$h ca$h ca$h)
I make between 400g and 2000g a turn.
Coastal cities build galeons and spies.
Science comes from trade and some scientists - and from tech stealing.
Step 7: Time to bribe Target: AI cities with wonders. First target:
The city with Adam Smith's in it (saves LOTS of money!).
2nd target: Pyramid city.
Wonders: Allt the wonders I couldn't build.
3rd target: Magellan city.
If the rival has democracy and switches to it, I switch to communism
and build tons of veteran spies (200 - 400).
My cities will celebrate under communism, too.
Those spies will poison the enemy's water supply again and again
until the cities are at size 1, so that the cities cannot support a lot of
troops.
Then I switch back to fundy and I build tons of veteran (->Sun Tzu's!) dragoons/cavalry.
With those it's easy to conquer or to destroy the enemy's cities.
At this point of the game I'm at war with each other civ. But
I put my focus on my strongest rivals.
Each bribed city will get a temple (to raise my income) and a market place
(->celebration!)
Cease fires won't last a long time (normally until the end of the turn, then the
AI will attack you again!)
Don't forget to switch back to demcracy from time to time (->WE LOVE ... DAYS)
in order to grow your population.