The two main types of positive reinforcements for dogs are praise and treats.
If your dog is a snuggly lover kind of pup you can effectively use praise, you will want to be consistent with certain positive phrases like "good boy" or "good" every time in a pleased excited voice. Praise can also include physical contact and affection like petting and snuggling your good boy after they properly follow a command or learn a new lesson.
If your dog responds better to food, you can use training treats. You will want to give your dog a single training treat every time they properly learn or follow a command or at the end of a training session put some treats into a toy designed to hold and dispense them slowly. This can be a bigger reward for a training session that went really well! The Mazeeis a great example of a treat dispensing toy that builds dogs logic skills and rewards them with lots of delicious fun. It can also be a good idea to switch the type of treat you use so that your dog doesn't get bored. Or if you are doing lots of different types of training with your dog it helps to find the treats that really motivate them well, high-value treats, and use those for the harder lessons your dog is learning. The harder the work, the yummier the treats should be!
Most owners and trainers use a balanced combination of both treats and praise for best results while using positive reinforcement with dog training. It is up to you to find the balance that works best for you and your dog.