How can you learn idiomatic expressions faster?
The best way to learn any language is to imerse yourself in it. If you cannot move to a place where they speak that language full-time, then order a newspaper in that language, watch television in that language, read books in that language, and use the internet to find websites in that language. The only way you are going to really learn to use idioms is to speak with a native, so either find some real people who speak the language and practice with them, or find a chat room for some internet practice. The problem with chat rooms is that you cannot see the body language and expressions that go along with the different phrases, but a chat room is better than no practice at all.