The way I've learned to use the speak the language best was to take works that are already written in Dovahzul and speak them out. Try to say them as normal sentences. Pay close attention to how everything sounds, as described in the Dragon-English dictionary.

You should eventually get a hang of speaking the language using what's already written.

Whilte you're doing that, try to speak out things around you in Dovahzul, or how you're feeling. Sometimes I can only say "Fin lok los bii" or "Zu'u koraav reythhe .. ko fin feykro." 

You'll stumble at first (which is natural for anyone), but you'll eventually start getting the hang of it.