You will need to print and take all forms with you. You can find the forms at https://travel.state.gov/content/passports/en/passports/forms.html If you currently have a passport, you will need to bring that as well. You will need to pay for the application in pesos or dollars. Currently, they do not accept credit cards. If your passport has not yet expired, they will let you keep it while they are processing your new passport. It will take 4-6 weeks to receive your new passport. Once the passport is ready, you will need to bring them your old passport so they can make the new one valid.
If you are renewing a passport for a child and both parents can not be at the appointment, they do accept a notarized form from the absent parent. You can find the form on the State Department website.
You will need passport photos for your application. You can get your photos taken at Foto Fiji in Cabo San Lucas. Foto Fiji is located on Juan Morelos. They are open Monday thru Saturday 9am-8pm. Directions: Located in downtown Cabo San Lucas. Take a right on Juan Morelos and go about two blocks. Foto Fiji is going to be on your right at the intersection of Juan Morelos and Revolucion de 1910. It is directly across from the OXXO. The cost is 120 pesos and takes about 15 minutes.