Canuck in Mexico on a whim (March)

[Scartoes]

I'm going to boogie woogie down on to Mexico with 3 or less paychecks for mid March, ideally I would like to visit Holbox and Oaxaca, stay for a month, airfare aside have less than 600 bucks and expect to sleep in the woods or on the street a lot. Is there any advice on the do's and dont's, I'm trying to pick up as much spanish as possible but are there any REALLY key phrases that most people don't think of? I'm pretty ok with the outdoors and love to hike so are there any must sees? and for someone who may have slept outside or got somewhere they shouldn't have, any advice?

Thanks guys,

Scartoes