I have been working on getting higher scores lately, using an early horseman rush to secure my continent, followed by peaceful building, followed by invasion of the other continent or continents, followed by some more peace. The objective isn't so much score as it is what I call "ultimate power." If I were playing for score alone, I'd have to play Huge maps. I can't stand huge maps, and don't really like large ones, so I play standard maps.
High score requires lots of land and people, the earlier the better. This, unless you employ the ICS Settler Flood Strategy w/exploits (TM, Aeson), requires early conquest. If you want a really high score, you must fight - and fight early. Though I think the scoring system is totally screwed up (weighted heavily toward bigger=better, no adjustment for map size, to name a couple of things), I have come to enjoy the power of early warmongering. That just leads to much higher scores, and I am trying to milk one of my recent games. There are limits on my milking, however. I will not sell off my libraries & universities to attempt to delay a cultural victory. No way. I will use more irrigation than I normally would in order to boost my population. I have stopped just short of domination, and will not build or capture any more cities.
To make a long story short, I play for fun (isn't that the point?), but I have done some milking for score.
-Arrian