One excellent tool for accent reduction used by linguists but often neglected in language education is IPA (international phonetic alphabet).
You can learn the portion of IPA relevant to the language you're working on, as well has how each symbol translates to mouth movements.
Then you can use the IPA transcriptions available in some dictionaries to not only hear how the word sounds when pronounced by a native speaker, but also know what they are doing mechanically to produce those sounds.
This is especially helpful, because it can train you to identify and produce the different phonemes that your brain isn't attuned to for in your native language (one classic example is japanese speakers' difficulty with r and l, which happens because different languages make different decisions about what constitutes a unique sound).
You can learn the portion of IPA relevant to the language you're working on, as well has how each symbol translates to mouth movements.
Then you can use the IPA transcriptions available in some dictionaries to not only hear how the word sounds when pronounced by a native speaker, but also know what they are doing mechanically to produce those sounds.
This is especially helpful, because it can train you to identify and produce the different phonemes that your brain isn't attuned to for in your native language (one classic example is japanese speakers' difficulty with r and l, which happens because different languages make different decisions about what constitutes a unique sound).