Try the basics first sit stay come. Make sure every training session is very short and fun. Chew toys are not to be used for training. Tease him with a bumper shaking it around for a bit and toss in a straight line from his eyes. When he gets it make a big fuss over him. When he get's it down pat, add your retrieve word such as fetch it up. Just a few tosses will do, his attention span is short. The play time can get longer as he gets older. Once he learns it all string them together. Have him sit, put your hand on his chest so he can't dart after it. Say stay. Tell him to fetch it up, allow him to bolt out. When he get's it call him back. Have him sit. As you take the toy back say release. Then instantly raise a big fuss over him. Do not throw any negative into it if he is a slow learner. You want him to love to retrieve and ultimately down the road his main priority is to make you happy by doing what you want when you want. He learns that he is having fun and it makes you happy when he does what he is supposed to. By doing the things he doesn't want to, such as sit or stay he is rewarded with fetch it up, so it's worth it.
One very important thing is that he learns to trust you completely. Later on when you are working on blind retrieves he needs to know that there is something there because you are telling him it is. Just let him be a puppy and don't get frustrated with him. He needs a stern voice at times to correct him, but he also has got to understand what he is doing wrong. In other words when he is doing something wrong you have to catch him doing it. Don't get mad if your boots are chewwed up and he's not around them when you see them. In that case leave them there until he wakes up and attacks them again and give a stern NO. If he is really unruly you can pinch an ear but do not hit under any circumstances,puppy or adult. If my grown dog's get out of line I will grab their jowwels, not to create pain but to keep them where I want them. My nose touches theirs and I very intently give a sharp no while staring them in the eyes. At this point they want to be anywhere but in that situation. The second they break eye contact I release. Then they approach and lick to show submission. We continue on with whatever we were doing I do not reward with treats only praise.