If you plan to live in Mexico you will need a FM3 visa (long-term, non-immigrant visa). Your tourist visa will only allow you to stay a maximum of six months.
Consider the local economy. Investigate immigration law and what is required in the way of a visa. You likely will not be able to work, at least not above board. Remember that being a tourist and being a resident are vastly different.
Take into consideration age and if you'll find competent Health Care, might not always be the case. Heard Merida has the best health care around, private HC is top notch... but alas! no beach!