We have discussed a lot about becoming a transcriptionist here on TranscriptionPro.
If you are interested but do not know where to get sample audios to practice transcription below is the link to download sample transcription audio files.
The completed transcription is also provided along with the sample audios so you can see how good your transcription skill really is.
Get your sample audio files here.
Sample audio files are both legal and medical.
One alternative to find audios or videos is Youtube.com, but I guess you already know that, right?