Questions about travelling in Mexico

[MartinW]

I think I finally have enough money to go to Mexico. I'm planning on going with this girl I know and was wondering if anyone could give me some advice. Does anyone know a good place to buy plane tickets from (I live in Ottawa)? Also, what's a good site to rent a hotel room from, and is it safe to hitch-hike alone in Mexico? I've hitch-hiked alone from Vancouver to Seattle and Vancouver to Ottawa and didn't have any problems, I'm guessing Mexico is more dangerous though. Are there any suggestions for where I should visit while there and any cool herps I should look out for? I know I need to renew my passport and get any vaccinations I may need but is there anything else I'm missing? Also, is anyone here from Mexico?

Edit: are cigarettes in Mexico cheap? I can't imagine them being as expensive as in Canada but I don't want any surprises.

Thanks,
Martin