Watching your puppy when he's outside place is crucial. If you don't watch him, you won't be able to prevent accidents. A good way to keep your puppy from wandering off and having an accident while your back is turned is to leash him and keep him at your side. He'll enjoy being with you, and you'll notice immediately if he needs to go out. Give him a toy to play with while he's next to you. If you're doing something that doesn't allow you to keep a close watch on your puppy, put him in his crate, playpen, or safe room. this will help prevent any accidents.
Every time you notice your puppy sniffing, circling, or squatting, clap your hands to get his attention and say "Outside? Do you need to go outside?" Then hustle him out before he has a change to do anything. Set a timer so that you remember to take him out every hour or two, even if he doesn't show any signs of needing to go out. Always take your pup out on a leash so you can see him potty, and praise him when he does. Giving a small food reward, such as a bit of kibble, immediately after your pup potties further reinforces the habit of eliminating outdoors.
Consistent positive reinforcement is the key to successful house-training.
It's very important that you go outside with your puppy. If you aren't there with him, you can't praise him for eliminating or teach him to go potty command. You also have no way of knowing whether he actually did anything. Many pet owners get angry because they send their pup outside and then the pup pees or poops when he comes inside. Without your guidance, your pup doesn't know why he's outside. If he hasn't performed after fifteen or twenty minutes, take him inside and crate him. Try again later.