I've faced the London System several times so far, and just don't know what strategy to adapt against it (I exclusively play Nf6 in response to 1.d4). I'm a highly tactical player, so I try following up with d5, c5, Qa5, Nc6, Rc8 etc. in order to break open the queen side when possible. But white just plays c3, e3 and curls up into an unbreakable shell. Then I end up getting outplayed positionally because I get frustrated and sac a pawn or two to get some activity.
So, is it possible to play both soundly and aggressively as black, with 1. ...Nf6 against the London System? Is there a way to entice white into doing something reckless? Or does white have complete control over keeping the game boring? What are the main strategic ideas for black (in general, with preference to aggressive options)? Also, I heard that the Colle system has the same reputation as the London system, and they are quite similar strategically as well. Is there a common way to deal with both of these systems?