I think there's no easy way of learning to make correct picks, you basically have to know exactly how the games work and you need to know intricate details about the players/teams.
I've made some successful picks in the past, on Starcraft for example, just because I'd been following one particular player while he was trying to move up the ladder.

I'd noticed that his game seemed a little bit off and decided to bet against him when he was playing against a slightly weaker opponent.
My gut feeling ended up being correct, since I made a nice profit from that game.

It's little stuff like this that you should take notice of.