Often times, hearing it helps considerably.
As long as sounds good when you say it, there are often 2-3 methods of pronunciations.

Myriophullum is a good example.
Taxonomist such as those that wrote the Jepson manunal pronunce it as Muh Rof Phil um. Other's: My Ro Phil um.

Both are correct BTW.

Regards,
Tom Barr