oki, as we're talking gotm, i expect we're talking difficulty below monarch. first off, let me admit i would never go for conquest victory, as i just can't see how taking every city on every island on a standard map could ever be quicker (in realtime, not in gameyears) than science/spaceship, religion/diplomatic or food/domination.
so far science/spaceship has been the easiest for me, just get 6 good cities during the course of the game, never adopt a state religion, say yes to all tribute demands except key technologies, say no to all dow/embargo, keep a well sized army to not appear weak at any time, and you should easily steer clear of any unwanted wars.
religion/diplomatic is a bit more tedious, but actually pretty fun i'd say. head straight for buddhism or hinduism, and convert all your fellow players. make sure you get a prophet asap for that holy shrine, and then pump out missionaries by the dozen. converting is actually pretty easy, just make sure your fellow players always have your religion in more of their cities than any other religion. build the UN, never propose free religion, don't leave anyone you ever attack alive.
and if you're neither a hardcore citybuilder, nor a religious fanatic, you can still comfortably go for domination. 1 war with macemen/knights, 1 war with gunpowder and 1 war with infantry/tanks should be enough to eliminate 3 of your fellow players and get domination on a 7 player standard map.
i've never played cultural victory but i assume it will work just as well with normal speed.
and then there's conquest. maybe conquest isn't meant for a game that goes into modern age? as one poster pointed out, conquest kind of goes hand in hand with UU rushes. as another pointed out, if your enemies are catching up to your war tech too quickly, maybe you're not crippling his research enough? and what if we're playing emperor and you don't have the technological edge to begin with? what's so great about getting attacked by superior technology twice as long?
sorry man, imho civ tech pace is well balanced. by the time anybody is researching from tank to modern tank you plain shouldn't be going for conquest victory anymore. what i'm more concerned about is the chop rush, i can't seem to shake this habit...