Too cute! Congrats on your puppy!
IME, the most important thing to know about chihuahua puppies is that they need a TON of socialization.... The world is a scary place if you're that small, and they need to know that they can trust you to keep them safe. Puppy classes are a MUST, so that they can learn how to get along with other dogs (many chis are scared/reactive toward other dogs), and frequent outings to meet new people is also a very important thing.
Good luck!!