We live in Carroll County in a 2200 sq ft and our BGE bill was $258 last month.
--I don't use the oven very much, especially, on hot, humid days. I love my electric pressure cooker!
--We've raised the thermostat to 76 on most days and it's been tolerable.
-- We put in an attic fan which has made a huge impact because upstairs is quite comfortable now. Before that, we would have to lower the temp on the A/C to cool upstairs.
--I keep curtains closed in the daytime for the windows with southern exposure.
--I keep toaster, coffee pot ,etc. unplugged when not in use
--we try to get the dishwasher when it's done and not let it go through the dry cycle for 30 minutes
--we've switched to fluorescent bulbs when our old lightbulbs die
--we've changed the settings on the water heater
--we only wash in cold water
--we take a lot of our stuff out of the dryer when it's damp and hang it up to finish drying
--ceiling fans in some rooms to circulate the air
I can't imagine having over $500 bill. Yikes

Try calling BGE and ask if they'll come out and do an energy audit.
As for Catonsville, I used to work there - that does count? I used to work at St. Agnes.