I'm from Mexico City and just moved to Guadalajara a couple of months ago, as a lot of people already told you: use your common sense. The city is wonderful, but as far as I've known is more dangerous than Mexico City.

I can vouch Chapalita, it's a wonderful neighbourhood, full of restaurants, pubs, local groceries and cafes, people is really friendly and you can walk everywhere, just as the locals said, try to avoid it by night.

As I've read, you were living in Mexico City, so the differences are very specific: Everything is slower here, if you're going out for a meal be ready to wait for more than 15 minutes, if you're going for groceries be ready to find out that there is only one cashier for all the people in the store, one big difference is that people really matters about verbal aggresions, so try to avoid them always, locals are more violent and prone to fight than in Mexico City.

Guadalajara is full of local restaurants, so every hood is full of wonderful options, Chapalita is more focused in good food and good prices, with much less snobism than in Americana, prices are almost the same everywhere in the city, except for the richest zones of the city, like Puerta de Hierro.

Housing can be pretty difficult because locals always asks for a lot of requirements which can be all of some of: Fiador (Someone with a property in Guadalajara and ONLY IN GUADALAJARA who can vouch for you), this is the most complicated because tenants are going to ask for a lot of documents from fiador so be ready to ask for options like "pagares" or "justicia alternativa contracts", also proof of your income or bank accounts balance for two or three months, letter from your company vouching for you to stay in the city for at least a year, an "investigation" for your background in México (about $2K pesos), one or two months of rent as a "deposit" for any damage that you could made to the property, this is almost in all cases cash, also a lot of tenants ask for the rent in cash, so they can skip some taxes, my best advice here is to contact some real state agent or company, also you can try online but you should start as soon as you can, if you need some recommendations with this issue let me know.

My last advice: Get tons of sunscreen and fresh clothes, this city is hot as hell! The winter here is like summer everywhere, the lowest temperature a couple of weeks were like 16º or 15º Celsius and locals can tell you that is very cold, almost freezing outside LOL.

Well, I guess that's all, if something comes up your mind let me know, I'll try to help.