actually i don't really agree with that, i think high level ladder games are often misleading because of sabotage picks and stuff, people might not understand the reasoning behind a lot of the picks (for example middle east is much more popular than it should be considering how bad it is as a spreading pick)
ais play completely differently from humans, so i don't think they're ideal to practice against except if you don't even know the most basic stuff.
I think the best way to improve is to watch commentaries on http://www.twitch.tv/wargaminglive
, because everything is explained perfectly. just find a strategic 1V1 series, preferably 1V1