need advice from dog owners here, please

hello, i have question for dog owners, how do you care for dogs? i never been around dogs long enough to care for one but i am looking to be a petsitter and a lot people have dogs so i want to know how to care for them properly.. do you care for them the same way you would for a cat? they're both very different animals so i do not know, i know that you need to walk, feed, water and play with them but is there more to learn about? i do not want to be careless when i take up a offer of pet sitting for a dog..