There are courses out there which teach good citizenship (see Good Citizen Dog Scheme), this usually includes teaching basic controls including sit, stay, down and recall. If you've got basic control over your dog walks are likely to be much less stressful as is socialising with your friends. Having control over your dog may one day save it's life if it's about to run out in front of a car. Think about it....
People who take their dogs on walks where they jump up at anyone and everyone, covering them in mud with a cheery 'oh, don't worry, he's just being friendly...' make my blood boil. These people have not thought about the fact that not everyone is a dog fan and some can find them downright intimidating, as they can't tell the difference between a dog that's being friendly and a dog that's being aggressive!!
Let me introduce you to The Dangerous Dogs Act, reading some of the small print lets us into a little known fact that a dog only has to frighten someone to be labelled dangerous do you want your dog to be responsible for giving a small child a lifetime of dog phobia all because you have omitted to teach your dog some basic manners? Do you want to end up in court the wrong end of an order to muzzle your pet in public because someone has misunderstood what your dog was trying to do, I DON'T THINK SO.
Dog ownership is a serious business, we need to teach our dog not to approach strangers unless we tell it that it's OK to do so. If the dog ends up in court, it won't be it's fault, it will be yours, nuff said!!
