Don't settle unless you have at least +2Happiness. Beeline for Constructions Mining->Masonry->Construction. If you are by yourself on a continent, initially focus on science. Create happiness buildings when you start getting low on happiness, but just keep expanding. I'm not going to say ignore culture, but, you don't have to make that a key focus. Eventually, at least what I've seen from my games on King level, though I'm slower initially, I can steam roll science, with a large empire quicker than anything the computer can do.
When you finally feel ready for the rivers to run red, build your army and navy. Declare war, let your naval units clean up whatever few ships the AI has, then start your invasion. Helps to bombard a city with your ship, as it gives the ship XP and lets one of your units take a city straight from coming of it's embarkation mode. If you have a few ships bombard units and take out whatever unguarded units the computer sends out.
As a point of advice, pick a city, if you are able to, that has a terrain based bottle neck. It will give you a good base to stage a defense until the computer whittles away it's army. That first city, I will say, annex it. If you have enough Gold, use it as a supply city. Buy units that you need to enable you to keep sprawl your way to victory. From what I've been able to experiment with, if at this point the computer offers you a peace offer that's beneficial to you, ignore it. You are able to wipe out his empire before long.
If you are with others, focus on initially on your army and then gradually, when you have a good defense in place attack one of you opponents. When you get a peace offer that favors you, accept it, otherwise shore up your newly acquired cities, and press forward. When you have good defense again, focus on a mix of money and science. You are basically doing what you did in the other way, but reversed. Military and then science, but finally going back to military.
Keep this in mind, I have only won victories in conquest and science. I turn off CS so it's impossible to win a diplo victory, and culture, being as I sprawl any more, is nearly impossible, except if I didn't try to be a warmonger. There is no one definite strategy that will win you victory step by step, it is all a matter of chance and reaction to said chances.
