My last two games at Hard I've won easily by the following strategy:1) Initially set all the Empire settings as low as possible. The goal is to keep every city at a happiness of 73. Build new cities as fast as possible until you have about 15. Spend gold and public works points as soon as you have them.
2) Be sure to get Ramayana; then most of your cities won't need any Happiness buildings.
3) Make a beeline for Monarchy and Republic. It's worth writing out this part of the tech tree and checking off each advance. Be sure to go to the Empire Manager and readjust your lowest happiness to 73 with each new form of government.
4) Once you have Knights and Samurai, start to conquer the other civ on the same continent. Since captured cities don't get damaged, this is much cheaper than founding new cities anyway. Go to Fascism when you have the chance. Build Fascist units, but with the intent that they will all die in battle. Once they are used up, you can switch to Democracy.
5) Periodically check happiness and boost the lowest cities by building a Theater or Arena. Otherwise go for science and production buildings.
6) As soon as you can build longships and diplomat, establish embassies with the distant civs. Park a diplomat outside their cities and hold a reception faithfully every ten turns. Get a peace treaty as soon as you can, and try for a research pact with whoever is farthest ahead in science. Go to Corporate Republic when you can,
7) Once you get up to about 35 cities, control every city on your continent, and have a good supply of cannon, machine guns, and cavalry, you look like a big threat. At this point, starting with the weaker civs, ask for an alliance and threaten to declare war. You may be pleasantly surprised at the result.
8) If you can't get an alliance with someone, build troop ships, park about 24 units outside a city, and threaten to destroy the city if they don't ally.
This strategy got me a diplomatic victory at Hard in 400 turns, before I had built a single tank.
I hope that winning is not this trivial at the hardest difficulty levels. I'm also going to try smaller maps.
I'm a pretty good Civ2 player -- I've won at Deity and have won at King with a single city. I can also win SMAC at the hardest level. I never played CTP1.