Teaching a dog how you want him to behave should simply be about teaching him what is "normal". You don't necessarily have to shout, tug or constantly tell your dog off to acheive this. In many cases how you behave around your dog is key as he will almost always follow your lead.
If you need to use corrective behaviour, keep the atmophere calm and be persistent - it's not always a quick fix.
Although not currently fully registered as a dog trainer, we have over 20 years of bulldog experience and are in the process of working towards Kennel Club Accreditation. We've seen aggressive dogs that are actually aggressive and agressive dogs that just pretend to be. If your bulldog is playing up - drop us a line and we will do everything we can to help you work it out
The most important part of any training is consistancy - things won't change overnight but we can hopefully help you find a way through