Accent reduction
For a given language, I return to pronunciation practice time and time again as I progress with a language. This is especially important when starting to learn a new language with new sounds that can temporarily interfer with other languages, even one’s native language.
In part, the sounds that you find problematic in a non-native language depends on your native language, your level of knowledge in the foreign language, how much you have worked on your accent until now, and other factors.
Using my training as a violinist and my advanced TEFL certificate, I analyze sound patterns and create practice exercises that target individual sounds and (more importantly) their connections to each to other.