You will know if you're in a bad area so I won't go over that.
Maintain situational awareness, not sure if you know or not but Chicago has had "teen" mob attacks on Michigan Avenue, even during the day. Check the knife laws as well, I believe Chicago is 2.5" while the rest of the state is 3.5".
Talking about food:
Johnny's in Oak Park has the best Italian beef and ice I've ever had
Portillo's has great all around food but they kinda skimp on the beef sandwiches, IMO
Gino's East has incredible deep dish though Giordano's is great as well
Do not put ketchup on your hotdogs, some places will tell you to leave
Maxwell Street Polish by UIC is the best, it's just east of Maxwell St. and Halsted near UIC
Be prepared to pay heavy for everything from the product themselves to the city tax.
And don't forget that the west side is also a criminal haven as well, it's not just the south side.
Remember, more people have been killed in Chicago than troops in Afghanistan.
Yes, I'm from Chicago and no, I do not miss it there one bit.
Giordano s is a must. Portillo s is ok. Wrigley field, chrome bean, John Hancock on 96th floor free to see drinks are high. Field museum and shedd aquarium gtg . Science and industry museum was not that great. DRINK LOTS OF 312 beer!!! Don't get off the train near or south of white Sox stadium.