I used to enter Mexico as a US Citizen and you were provided a card on the flight that you completed, where you would enter the address of the property you were staying, along with your passport and boarding pass information (so hold onto that). Since I'm a Mexican resident I no longer need to get a tourist visa but it's supposedly easier now as the paper form is no longer needed at the majority of the airports in Mexico, as they are processing entries electronically and will stamp your passport. Make sure you tell them how many days you need including a few extras just in case. Many visitors are getting 6 months.

Forum members will stop by to give you more recent updates, but if you could identify the airport or port of entry you plan to use it will help give you the most updated information.

And you don't need to show proof of funds or address etc.