Check with your local SPCA and see if they offer obedience/training classes. Our last two benefited greatly from these programs. Gets them around other dogs and people in a controlled environment.
Our current lab spent the first year of her life alone in a back yard. We brought her home and she was good but constantly scared to the point of anxiety attacks. After a few anxious classes on our part she started to come around.
With our last queensland and with this lab one of the biggest things we have learned is that they need jobs, something to help occupy there time and give them a routine and in a way a purpose. The start of the day she goes out and gets the newspaper and brings it to the chair. On mornings where we are moving slow and she doesn't have a chance to get the paper you can see her getting agitated and anxious. As soon as we let her get the paper she calms right down.
We don't have to do it now but for a few years we had to carry a ball or stuffed toy everywhere we went. If we were out and something or someone spooked her she would get mouthy and it came across as aggression. I don't think she would bite but to help avoid it we would make her carry the ball or toy any time she got her self worked up so her mouth was full. It has become a safety blanket of sorts. Now at 10 years old we just have a ball close by and when she becomes anxious she will find the ball her self. It is almost like she has learned that when she gets that feeling it is her job to get the ball. Having the ball in her mouth also keeps her from barking which is a trait I don't think we will ever break her of and it is the standard deep lab bark that comes across as aggressive and would always escalate emotions of everyone around.
Also if you find your dog likes to play fetch having a ball on hand is a great thing. No one can see a lab with a ball and not want to play fetch with them. The more people play fetch with our lab she becomes focused on the game and gets tired which in turn makes her pay less attention to all the things around her that would trigger the anxiety.