Show the pup your the Alpha dog. Eat before it does, walk through doors before it does and teach it to do as you say. Thats it in a nutshell but its obviously alot more involved than that. Treat it as a dog, however lonely and sad you are its not a kid so putting it on the naughty step will not work, they need a firm hand as thats how they learn in the wild.

If you have no clue then lessons can be good but tbh I never took mine as I have been raised with GSD's and he is better trained than 99% of the dogs that come out of there.

Use one word commands, not sentences. NO should be your favourite along with Well done (with praise). The amount of handlers I see saying "don't do that fluffy its naughty and mummy is not in the mood" astounds me.

Puppy socialising classes are fine but taking it up town to be petted by all passers by is better, take it to other areas where dogs go and also by mains roads etc to get it used to traffic. Go stand outside the school gates at home time and it will soon get used to strangers.