What do you mean you can't determine the sounds? If you mean you can't imagine the phonemes, interactive IPA charts like this one may help; if you mean you can't decide on the language's phonemes and phonotaxis, maybe you could piece it together from existing languages'?
(And while I agree dragons named Pamela are silly, I wouldn't say a character can never have a name that coincides with a contemporary Earth name; as long as the character name makes sense in from their culture's naming patterns.)