What can I do to lower my electric bill?

I'll be living in a 3 bedroom house with 1 bath that use to be my parents. The electric bill is roughly around $400. So I want to know what could I do to the house to lower the bill? My mom and I were talking about buying new windows because they're old. But what else is there than the most common to conserve energy (which we already do). Its a old house so I know its common for older houses to have a high electric bill.