I've had an account here for years, but only a few months ago got a set of lockpicks and started actually doing it. Since then I've been picking the same set of 4 padlocks (I lost the keys years ago :S). Anyway, most locks I've found are similar in design to the padlocks I've been playing with.
However, the external doors on my house are really old, with big chunky keys. They look completely different to the padlocks (padlocks are called pin tumbler locks I think?), and work differently. The padlocks have to only be turned about 30 degrees to open, these have to do about 2 revolutions.
Here are the keys:

I don't know how else to describe them, but I really want to try to pick them. My tools will hardly even fit the keyway (it is pretty thick), and the key is such a different shape I doubt it has the same mechanisms :S
Can someone tell me how to pick this?