Reading various books and websites such as those being mentioned by others in this thread, not to mention listening to other hobbyists, is very useful. Beyond that, my best advice for how to pronounce Latin scientific names is "with confidence." If you speak them like you know what you are saying, very few people will question how you do it. For those few who might question you, you can simply roll your eyes at them
as if to say, "Are you kidding?" Getting it "wrong" (different from how someone else does it) is not a big deal.
If you are worried about being understood, just add a bit of text to your presentation, spelling out the names so your audience members can read them while you pronounce them.
Don't let this limitation slow you down! If people are asking you to speak, it probably means they know you have good info to share and we all like "good sharing."
Chair, American Cichlid Association (ACA)
President, Oklahoma Aquarium Association (OKAA)
ACA 2012 Convention in Indianapolis, INhttp://www.aca2012indy.com