Hi Juan,
Great question. Romeoville is a great rental market. Start looking at properties and use Redfin, Zillow, Trulia, realtor.com, MLS etc. If you become an expert in your market it will become easy to weed out the ones that are not a good deal. Watch other flippers or buy and hold investors.
When I started I went to numerous REIA Real Estate Investment Associations to learn. I picked a market and watched what people paid for property and then they would reappear on the market 6 months later. If you look at pictures you can see what they did to the properties and you can estimate the rehab cost and profit. I looked a t a lot of properties to get a good idea of what people were doing.
If you become an expert in your area your comfort level will increase and will lower any apprehension you might have.
A friend of mine does a lot of buy and holds there. He currently buys most at auctions, but in the beginning he used the MLS. He was able to acquire about 18 units within 30 months.
Good Luck.