Road food and delicate stomach: useful rules without ruining the journey

I love to try markets and stalls, but after a bad intoxication I became too prudent and I end up in the tourist premises. I will leave for Mexico and Guatemala and I would like to find a reasonable balance. I know that zero risk does not exist and that hygiene is not judged by the tablecloth. What signs do you observe, how do you manage water and ice and what do you bring to face a problem without improvising drugs? ♪ mainly affects a comparison based on recent experiences: indicated travel period, what really wor…