How do I play against Handlock?

Handlocks seem to be in favor currently, at least I'm encountering them far more often than I used to. But I still don't have a good idea on how to actually play against them effectively.

In the game I just played I was rather close to being able to burst the Handlock down in one turn. A turn later he had three molten giants out, two of them taunted. I obviously lost that game.

I have tried to play around molten giants in the past, that didn't work out all that well either. The opponent simply tapped again, and was then able to play the molten giant. At best I could delay it one turn.

I'm currently playing Shaman, but I'm interested in general rules for all classes against Handlock. What are the general strategies against Handlock? When should I play around the molten giants and avoid hitting the enemy hero, and when should I go for direct damage?