Tim's 10 Tips for Mexico Travel

While it is fresh on my mind, here are my 10 tips for travel in Mexico.   Basically posting on here also so I'll have them and can reference them later, but here you go in no particular order:

1. Even if someone says "it's ok, it's filtered", *never* drink the water.
2. Take US made Immodium AD with you.  Don't buy the cheap "loperamida" stuff at the Mexican farmacia (if you have to, buy the most expensive one they offer!)  On the same note, tell your doctor you are going to Mexico and ask for a Z-pack to take with you (or likewise, buy they best one you can get at the farmacia if needed.)
3. Pay in pesos when possible!  You will get a much better deal.  Likewise when asking for cost, ask in pesos, not US dollars.  
4. Try and learn some Spanish.  Even just the effort of speaking horrible Spanish will at least get locals to warm up to you.  They appreciate the effort you are putting out.  
5. Before you eat somewhere, figure out where they handle their sanitary needs.  Sure the iron gut locals who have built up a tolerance for the venom can eat at any roadside taco stand, but I bet $10 in Immodium your gringo gut isn't going to do that well at the same space.
6. If you know Spanish and a local wants to talk to you in English, don't force them to use Spanish.  I found many young professionals liked flexing their English as much or more than I like flexing my (wimpy) Spanish muscles.
7. Don't throw your clothes in plastic bags, etc. when entering Mexico.  It is illegal to take in used clothing and if it isn't packed in a suitcase like it is yours, it will either be liberated for the border attendant's usage, or you will need to take it back to the states.
8. "La cuenta por favor!"  Unless you want to sit there forever thinking your wait staff is ignoring you, ask them for the check!  They think it is rude to bother you and rush you on your way by bringing a check.  Ask for it!
9. Do not speed and stop at every ALTO coming to a complete stop!  Locals will be flying by you and treating stop signs like yields, but they are locals and la policia has no interest in them.  On the other hand, you are a gringo and are ripe for the picking.  Don't give them an excuse. 
10. Never assume that a restroom will have toilet paper (or even a seat... it could just be a bowl.)  I learned to keep TP in a sandwich bag in a cargo short pocket and was very glad I did.

I'm sure there is much much more and a Google search will get you more than you ever wanted to know.  But, this is my humble offering from experience on my last trip.