You get points whenever you complete an area. You get more points if the area is bigger, and also if you complete it in earlier phases. There is also a big bonus for being the first player to finish all of one colour (so far, Watno got it for grey, I got it for dark green) and a smaller bonus for being second, I think.
You didn't really have a choice with those mines, I think? Watno scooped the only one in the first round, then he scooped another two in the second round and I grabbed the last one. And I just grabbed yet another in this round. I don't think you ever had a chance.
I'm curious about first player advantage in this game. Watno managed to grab some really great stuff -- all the mines and the +/-2 science tile. I feel like I made a really good play in my first turn of the game, grabbing that Bank so that I could scoop the +4 workers science tile. Man, if Watno had gotten that AND the +/-2, it would have been insane.
You're doing good too though. If a couple of cow tiles show up, that field area is going to earn you TONS of points.