Welcome to the forum! One of the best books is Chihuahuas For Dummies. (other than the name of course!) It goes through the pets life from being born to euthanization. It is one of the Dummies books of which there are gobs it seems.
One of the best things I recommend is the Iris pen. A pen with a bed (washable please) and her bowls and a few chew toys (look for Kong puppy chews) and a washable human grade pee pad. I like these - the size is 34"x36" and last for years. Do NOT add anything to the wash except detergent. No softeners or any other add in. Mine have lasted over 4-5 years! Dry on low heat with no add ins- ie dryer sheets. They do something to the fabric. The pen keeps her safe when you are not able to watch her. A harness, and leash, water and food bowls _ small please, and some toys. She will be teething, so a frozen face towel, twisted up might help those sore gums. Make sure you are watching her when you give it to her. You might have a crawl around to see if there are any electrical cords, or other no chew items. something called Bitter Apple wiped on cords makes them icky to the pup! You also might want to invest in some honey or some such sweet item, so if the pup suddenly gets a low blood sugar, you can give some to her. Make sure you can feed this wee pup 4X a day, and I would leave some dry food out at night. Good luck, and come back if you have any questions.