Check the Chicago River forum section. Some have posted recently where they've caught some gills. Since you're in the Ravenswood area, Foster ave is real close to you. Other spots along the river would be Howard and McCormick or Oakton and McCormick. Another spot a little further north would be the Skokie Lagoons. The bridge area at Willow and Forestway Drive has some gills. Pick up some wax worms at Fish Tech on Dempster St in Morton Grove and you're good to go.
NOTE: The bridge area I speak of is NOT the road bridge on Willow Rd. Turn north onto Forestway Dr and you'll see cars parked along the west side of Forestway (about 150ft north of Willow Rd). Pull in (watch out for the southbound traffic!) and park. Walk to the bridge and drop a line.
The key to catching gills is to show them something different. They are so used to seeing big hooks and red and white bobbers with worms that they will just ignore it. Get some good small wood bobbers and use ice jigs or mini jigs tipped with wax worms. You could even use flies. Belleau lake is a good spot, we saw lots of gills out there. Gills are not like bass. They spawn for months, so they will be on the beds at least for another month. Even big gills feed on small bugs and larva, so keep it small.
Custom Jigs n spin Ratso or Rat Finkie, under a slip bobber rig. Many times bait's not even needed, though I like to use a bit of Berkley Powerbait Honey worms. Any forest preserve pond, and virtually ANY subdivision pond if you're not picky on size (many don't have bass to control population, so you end up with thousands of ravenous, 2-5" in gills. If the pond is posted, knock on a couple doors to ask for access....just be sure to leave it better than you found it.