For Puppies

Feed them good quality food - Good quality foods will make their stomachs stronger! Young puppies start their life with their mother's milk or formula, so they need to be eased into eating solid food. Sometimes dogs still drink milk after their teeth grow in (unless they are an adult) for comfort. Mostly, if you adopt a puppy, they are already eating solid food. Be sure to buy dog food specifically for puppies.

Play with them! - Puppies are very active and playful, just like us when we were kids. They need to use that energy somewhere. So, whenever you get the chance, play with them! Puppy playpens filled with toys are a good choice if you can't play with them but are at home. Chews can be used after dogs have their teeth grown in but always must be supervised.
Train them - Training them will help you tons in the future. They will follow all your commands, which will make taking care of them way easier.
Puppy-proof your house! - Make sure you make your house so that the puppies won't do or eat something they shouldn't. You should remove all little toys in case they ever think it's food and make sure nothing that they will chew ( except their toys ) are lying around. Don't use soft dog beds until they are house trained so they don't wet the bed.
Buy supplies! - Like humans, puppies need supplies like toys, collars, a bed, and more!
Give them some love! - Unless you give them love, puppies won't be happy!