Suggestions for estimating Rents/taxes/expenses

[Joshua McLean]

While analyzing deals in my local Cleveland market, I am always looking for way to come up with more accurate  estimations for what I could expect to be rents, utilities, and property taxes.  Currently, I use Rentometer to estimate my rents, the listing description for taxes, and I use an educated guess  for the utilities. I know how important it its to really be confident in your numbers, but I feel like I am leaving a lot of play with these numbers. What suggestions are there to help me hone in on taking in my numbers and feeling more confident in the math?