Positive reinforcement. Assuming you give him regular dry pellet-type food, keep a small baggie of it in your pocket and give him one or two pellets EVERY time he does anything he's been told (come, sit, down, heel, fetch, stay, whatever.). Also, vary your commands, dogs will get bored if you ask them to do the same thing over and over again, even if he just knows 4 or 5 commands (like most dogs), keep the dog on it's toes by never issuing the same command twice in a row.
You can also try to get the dog a "special" collar, basically a collar that the dog only gets to wear at "work", pretty soon the dog will associate the collar with fun, praise, and most importantly EXTRA FOOD. If you decide to go with that approach though it's very important that you ALWAYS insist on your commands being followed through, much more so with the collar on than off, that establishes "dominance" between you and the dog, dogs are smart critters, soon the dog realises what's expected of him, knows he won't get away with not doing it, and besides, it's a lot more fun for him to get a food reward than a stern NO! and an annoyed boss...
The thing of it is,I'm not doing anything different than with every other dog I've owned
