The best strategy for health insurance in Mexico, is the one that is tailored specifically for you. If you read all the valuable contributions shown so far, you are on the right track. You would know already that there are many options available, but, with those many options, which one is the best for you?
I lived in the US and then in Canada for a few years and was always told to get the advice of a licensed local Insurance Agent. Better an independent broker, used to compare different carriers and plans, and suggest what better suits you. The same advice is valid in México. Nevertheless, if you still don´t have your residency card, Mexican insurance companies may not write a policy for you, for legal and underwriting reasons.
Then you have to resort to certain carriers that are all around the world, which offer International Health or Travel Insurance. They sell through Internet or through travel agents, who are advised "Not to play the Insurance expert", because they are not licensed. They may be based in Hong Kong, Cayman Islands, Virgin Islands, Bermuda, Ukraine, etc., and their operations may or may not be supervised by local authorities. Some have commercial offices in America. There is nothing wrong a priori, because we here are all "International" and open to different cultures and ideas, but if you are not very familiar with health insurance concepts, limitations and procedures, mostly because you have relied on your local provider, it is critical for you to get the help of an agent who can tell you how things really work in Mexico, and also see what is available all around, and how can you combine, let´s say your Provincial Care, your Medicare, your parts A, B, or your supplemental coverage, with the Health System in México. See if you can use it here, or at least get reimbursed for money spent here, and then, how can you get the proper documentation to request reimbursement back home.
It is a big issue. Legislators and authorities are still working on how the International Insurance Products can be sold in a practical, safe way to consumers, because there is a real need. Even American Carriers are cautious. Few offer International Coverage, or do it through their off-shore units.
Then, we have the "consumer groups" or "clubs" which are even championed by opponents to Obama Care, as the alternative for making health care affordable, But please remember, health care is expensive by itself, and there are insurance carriers who have hundreds of thousands of participants in their book of business, who get eaten by the loss ratio. Forming groups is not a new idea in México. We had our experiences during the 80´s and 90´s, with results so bad to insurers and clients, that the authorities had to make changes in Laws and Rules.
The cost of Medical attention in Mexico, is about 30% of what would cost in the US and Canada.
If you wish to get quality attention, then your Insurance premium should be about 30% of what costs in your country, deductible no more than 30% of your foreign deductible, and works very different.
Discounted prices will buy you discounted coverage.
The average claim paid by Mexican insurance is about $4,000 US Dollars. Insurers negotiate lower rates with providers. If you go straight to the doctor or hospitals you can be charged twice as much. For those reasons I suggest your deductible in Mexico to be between $1,000 and $1,500 USD. It works per each illness. Very different from US or Canada.
With a $4,000 or higher deductible you would be excluding most medical procedures and treatments performed in Mexico. The worst part, is when need a medical treatment, but you estimate that would have to be paid out of pocket because is lower than your deductible, you may give up your access to quality providers and go to a cheaper, almost gray market, which can become costly.
Mexican insurance companies have different age limits, exclusions, waiting periods, regional rates, many combinations of deductible and co-insurance, as well as quality tiered network providers. Some speak English, most don´t. So, really please get a good agent. It won´t cost you more, and can make a difference in one of your highest priorities while abroad-- your health.
Yes, you have to pay US income tax on money that you earn in Belize. However, there are exclusions that you can claim such as the Foreign Earned Income Exclusion, which will allow you to exclude a certain amount of money (around US $100,000 each) for you and about the same amount for your spouse to exclude that for tax in the United States. However, if your earned income is above that, then you have to pay income taxes in the United States. 
The answers submitted so far have been very general because the question was so general. The reply to check up on health insurance is a very good one, but there is a lot more. 
Nicaragua’s legal currency is the Cordoba, but US dollars are used for the economy. The prices you see are in dollars. For example, food prices in restaurants, for cars, houses, and a lot of appliances are in dollars. Telephone companies sell their models in dollars. Businesses still take Córdobas, but the dollar is freely exchangeable. 
High quality, broadband Internet service in Portugal costs about €10 (US $11 or £7.50) a month. The country’s aim is for Internet service to be free for everybody by the year 2020. The reason why the Internet connectivity is so cheap in Portugal is because the government subsidizes it. 
Having lived in Belize as an ex-pat for almost 30 years, I guess I qualify as a bit of an expert on the country. 
