In Illinois, first-time homebuyers should be aware of common mistakes to avoid during the homebuying process. One key error is delaying mortgage preapproval, which helps establish a realistic budget. Additionally, it's important to shop around for mortgage lenders, as interest rates and fees can vary significantly. Buyers should also be cautious not to borrow the maximum amount offered, as high mortgage payments can lead to financial strain. Lastly, maintaining a stable credit score is crucial, as changes can affect mortgage offers.