Record yourself

Just as people are often shocked when they hear a recording of their voice for the first time ("Oh my goodness! Do I really sound like that??"), you will be surprised by how many of your own pronunciation mistakes you can pick up just by recording your voice and playing it back. You can make that even more effective by playing back the model recording and your own recording at the same time or one just after the other. This is most easily done on a computer, or in an old fashioned language lab with the two parts recorded on opposite sides of a cassette. There will still be plenty of pronunciation points you miss, for example vowel sounds that you can't even hear the difference between, but you should be able to get your rhythm and pausing almost perfect just by doing this.

You could also listen to a recording of yourself while just listening for one sound that you want to work on, e.g. making sure that your th sounds don't sound like s, or that you don't miss out h sounds.

Nowadays there are also computer programs and one or two sites that show you a wave form analysis of your voice and compare it to the wave form of the voice that you are copying. Most of the programs then give you a score, e.g. 76 points for being 76% similar to the model recording. It is as amazing as that sounds to see that up on the computer screen, but there are still all kinds of technical and practical problems with this system. One issue is that equal weighting is given to unimportant things like exactly matching the tone of the speaker and important things like stressing the right words. The other thing is that there are actually many other perfectly correct ways of saying the word or phrase, but you have to copy the (perhaps idiosyncratic) version that the computer is producing. If you are copying someone with a different age or gender, you might not want to copy them 100%! Nevertheless, getting visual clues or a score is very motivating, and I spent longer on a Japanese CD ROM that did this than any of the other language learning games and other materials that I was using at the time. It also made me listen to my own production very closely.

You could also try videoing yourself and checking your mouth shape against the original speaker or a model mouth shape.