The earliest exercise to start with is simply placing your puppy in the sit position as you give him the sit command. Keep your hands on the puppy to help him hold the position for a few seconds, then praise him lavishly, emphasizing the sit word. "What a good SIT!". Keep your voice happy, light and joyful when you praise. Then place the puppy in the down position as you give the command to down. Make your voice deeper and more authorative when giving a command. Puppy may struggle more in the down position, hold him in position until he relaxes in your hands, then praise him for his wonderful down. Next, place your hand just under his thigh to help him stand. Place his feet four square under him and hold him in position as you tell him to stand. Then praise, praise, praise! Repeat these exercises five times each. Very soon your puppy will anticipate your commands and will sit or down without you having to place him in position. This is a big step forward and deserves extra praise.
Try to find a puppy kindergarten class, classes are often offered by community adult education. Ask to monitor the class, see if you like the trainer's methods. Puppy's shots will have to be up to date before you take him out to a public place and most trainers will require proof of vaccination. Socialization is imperative, puppy needs to learn that the world is a good and safe place. Ask your vet if you can bring your puppy in for a social visit. Bring a pocket full of treats and have everyone make a fuss over your puppy. There are pet supply stores that welcome pets, here is another opportunity to give your puppy a positive experience. Little league games, soccer and auctions are also great places to socialize a puppy.