Tips for dealing with a growling or biting dog:
Consider contacting a Veterinary Behavioral Specialist for a consultation.
When searching for a trainer, make sure you find one that is experienced with aggression and is planning to use positive methods to alleviate your dog's aggressive associations.
Avoid using "corrections" or punishments. The idea will be to teach him positive associations with the things that currently upset upset him, using baby steps. Here is an article on working with your aggressive dog.
Most importantly, do your best to prevent eliciting the aggression and keep everyone safe!
The products below will help you to teach your dog to be less aggressive.