I regularly meet with a small group of other learners of Standard Chinese. They have been learning Chinese for several years, though not as long as me. One of their problems is pronunciation, especially pronouncing the tones correctly. For example, the fourth tone (a falling tone) does not sufficiently "fall" and the second tone does not sufficiently "rise".
One consequence of the bad pronunciation of the fourth tone is that it is difficult to hear the difference between, for example, 哪里 (nǎlǐ: where?) and 那里 (nàlǐ: there). This can lead to confusion, especially in dialogues where both words are used. (Chinese does not use sentence-level intonation to distinguish between affirmative sentences and questions. So pronouncing question words correctly is essential for understanding.)
How can I help other learners of Standard Chinese to get the tones right? Especially without being a native speaker myself?