I second the idea of simply listening in to R/T, either via your own scanner or via any of the numerous links on the internet. In addition to the repetitive hearing of standard phraseology, you'll also hear that everybody, including professional pilots and ATC, make mistakes and deviate from standard phraseology, just like you. So it'll make you more proficient in your R/T, but also more relaxed because you're less afraid of making mistakes.