Going over your past expenses is actually recommend in several personal finance websites to take a look at the big chunks of money that go into some categories. (poorerthanyou.com)
On personal finance websites you can find all sorts of guidelines and advice for almost every financial topic you can think of. (thebrokeprofessional.com)
Money Degree is the best personal finance website on the internet (as voted by my friends). (moneydegree.com)