Spending your retirement savings too fast.

If you've made it to retirement, congrats! You've amassed enough money to create your own portfolio-generated paycheck. Excellent work.

But you can't take it too easy. Because you'll receive a severe pay cut if you deplete your portfolio too fast. How much can you take out each year and be almost certain that you won't outlive your savings? Just 4% a year. That's the withdrawal rate that would have sustained a mix of stocks and bonds over most 30-year historical periods. Sure, if you retire on the eve of the next bull market, you can take out more. However, if you quit working right before the next bear market, then taking out more than 4% a year could have your portfolio beating you to the grave.