Why Smart People Make Big Money Mistakes by Gary Belsky, Thomas Gilovich.
If you read two finance books in your life, read this book twice.

One author is a psychologist, the other is a writer for Money magazine, and together they walk you through the developments in behavioral economics (which studies how we make economic decisions). Unfortunately, there are financial mistakes us humans commonly make, so it's more a matter of being aware of these pitfalls. This book describes these errors and more importantly, why they are counter-intuitive.

If you're not going to read it (shame on you!), here's the list of steps you should take (listed at the end of the book):

  1. Raise your insurance deductible
  2. Self-insure against small losses
  3. Pay off credit card debt with emergency funds
  4. Switch to index funds (ETFs nowadays)
  5. Diversify your investments
  6. Review your assets
  7. Max out your contribution to retirement plans
  8. Set up a payroll deduction plan
  9. Keep track of your investments!