Entrepreneurship - Online business (Mexico City)

Hi everyone!
I'm currently working on an e-commerce business idea and was wondering whether anyone here could provide me with some insights.

Do any of you run an online business? If so, in terms of shipping your products to customers, which shipping companies do you recommend?Do you ship to other cities within the Mexican territory? To other countries? What are the costs for each of the aformentioned options? What kind of agreements have you reached with shipping companies?

Many thanks and kind regards,
Sandra