[ylyn]

That's actually fine. (I'm a native bilingual speaker, although not from PRC.)

Also, the 3rd tone is characterised more by being low than the fall-then-rise. In fast speech the rising part is often not heard; it's only really present in stressed syllables or possibly at the ends of sentences.

[drenvuk]

Any tips for the ü?

[kenneth]

As a native french speaking, the mandarin nǔ is one of the few things I actually find super easy. Helps that we have the exact same ü sound in french.

[yorwba]

yu combines the tongue position of yi and the lip rounding of wu. Being able to take apart the individual components of a sound and consciously reassemble them into something different is very helpful for language learning.

If you're not sure what the components are, try reading the corresponding Wikipedia article (usually linked in the phonology section of the article about the given language): https://en.wikipedia.org/wiki/Close_front_rounded_vowel